diff --git a/proto/backend.proto b/proto/backend.proto
index c9435c7d4..c830225c7 100644
--- a/proto/backend.proto
+++ b/proto/backend.proto
@@ -12,6 +12,7 @@ message BackendInit {
     string media_db_path = 3;
     repeated string preferred_langs = 4;
     string locale_folder_path = 5;
+    string log_path = 6;
 }
 
 message I18nBackendInit {
diff --git a/pylib/anki/rsbackend.py b/pylib/anki/rsbackend.py
index b5f10f8dd..6ff70d95d 100644
--- a/pylib/anki/rsbackend.py
+++ b/pylib/anki/rsbackend.py
@@ -179,7 +179,7 @@ def proto_progress_to_native(progress: pb.Progress) -> Progress:
 
 class RustBackend:
     def __init__(
-        self, col_path: str, media_folder_path: str, media_db_path: str
+        self, col_path: str, media_folder_path: str, media_db_path: str, log_path: str
     ) -> None:
         ftl_folder = os.path.join(anki.lang.locale_folder, "fluent")
         init_msg = pb.BackendInit(
@@ -188,6 +188,7 @@ class RustBackend:
             media_db_path=media_db_path,
             locale_folder_path=ftl_folder,
             preferred_langs=[anki.lang.currentLang],
+            log_path=log_path,
         )
         self._backend = ankirspy.open_backend(init_msg.SerializeToString())
         self._backend.set_progress_callback(self._on_progress)
@@ -382,3 +383,8 @@ class I18nBackend:
         return self._backend.translate(
             translate_string_in(key, **kwargs).SerializeToString()
         )
+
+
+# temporarily force logging of media handling
+if "RUST_LOG" not in os.environ:
+    os.environ["RUST_LOG"] = "warn,anki::media=debug"
diff --git a/pylib/anki/storage.py b/pylib/anki/storage.py
index 03f1a16aa..665291cfd 100644
--- a/pylib/anki/storage.py
+++ b/pylib/anki/storage.py
@@ -33,7 +33,10 @@ def Collection(
     "Open a new or existing collection. Path must be unicode."
     assert path.endswith(".anki2")
     (media_dir, media_db) = media_paths_from_col_path(path)
-    backend = RustBackend(path, media_dir, media_db)
+    log_path = ""
+    if not server:
+        log_path = path.replace(".anki2", "2.log")
+    backend = RustBackend(path, media_dir, media_db, log_path)
     path = os.path.abspath(path)
     create = not os.path.exists(path)
     if create:
diff --git a/rslib/Cargo.toml b/rslib/Cargo.toml
index 6f4a9cec4..65c085a67 100644
--- a/rslib/Cargo.toml
+++ b/rslib/Cargo.toml
@@ -23,9 +23,7 @@ serde = "1.0.104"
 serde_json = "1.0.45"
 tokio = "0.2.11"
 serde_derive = "1.0.104"
-env_logger = "0.7.1"
 zip = "0.5.4"
-log = "0.4.8"
 serde_tuple = "0.4.0"
 coarsetime = "=0.1.11"
 utime = "0.2.1"
@@ -34,6 +32,10 @@ unic-langid = { version = "0.8.0", features = ["macros"] }
 fluent = { git = "https://github.com/ankitects/fluent-rs.git", branch="32bit-panic" }
 intl-memoizer = { git = "https://github.com/ankitects/fluent-rs.git", branch="32bit-panic" }
 num-format = "0.4.0"
+slog = { version = "2.5.2", features = ["max_level_trace", "release_max_level_debug"] }
+slog-term = "2.5.0"
+slog-async = "2.4.0"
+slog-envlogger = "2.2.0"
 
 [target.'cfg(target_vendor="apple")'.dependencies]
 rusqlite = { version = "0.21.0", features = ["trace"] }
diff --git a/rslib/src/backend.rs b/rslib/src/backend.rs
index 0f76a049f..842011101 100644
--- a/rslib/src/backend.rs
+++ b/rslib/src/backend.rs
@@ -1,12 +1,12 @@
 // Copyright: Ankitects Pty Ltd and contributors
 // License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 
-use crate::backend_proto as pb;
 use crate::backend_proto::backend_input::Value;
 use crate::backend_proto::{Empty, RenderedTemplateReplacement, SyncMediaIn};
 use crate::err::{AnkiError, NetworkErrorKind, Result, SyncErrorKind};
 use crate::i18n::{tr_args, FString, I18n};
 use crate::latex::{extract_latex, extract_latex_expanding_clozes, ExtractedLatex};
+use crate::log::{default_logger, Logger};
 use crate::media::check::MediaChecker;
 use crate::media::sync::MediaSyncProgress;
 use crate::media::MediaManager;
@@ -17,10 +17,11 @@ use crate::template::{
     RenderedNode,
 };
 use crate::text::{extract_av_tags, strip_av_tags, AVTag};
+use crate::{backend_proto as pb, log};
 use fluent::FluentValue;
 use prost::Message;
 use std::collections::{HashMap, HashSet};
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 use tokio::runtime::Runtime;
 
 pub type ProtoProgressCallback = Box<dyn Fn(Vec<u8>) -> bool + Send>;
@@ -32,6 +33,7 @@ pub struct Backend {
     media_db: String,
     progress_callback: Option<ProtoProgressCallback>,
     i18n: I18n,
+    log: Logger,
 }
 
 enum Progress<'a> {
@@ -101,13 +103,28 @@ pub fn init_backend(init_msg: &[u8]) -> std::result::Result<Backend, String> {
         Err(_) => return Err("couldn't decode init request".into()),
     };
 
-    let i18n = I18n::new(&input.preferred_langs, input.locale_folder_path);
+    let mut path = input.collection_path.clone();
+    path.push_str(".log");
+
+    let log_path = match input.log_path.as_str() {
+        "" => None,
+        path => Some(Path::new(path)),
+    };
+    let logger =
+        default_logger(log_path).map_err(|e| format!("Unable to open log file: {:?}", e))?;
+
+    let i18n = I18n::new(
+        &input.preferred_langs,
+        input.locale_folder_path,
+        log::terminal(),
+    );
 
     match Backend::new(
         &input.collection_path,
         &input.media_folder_path,
         &input.media_db_path,
         i18n,
+        logger,
     ) {
         Ok(backend) => Ok(backend),
         Err(e) => Err(format!("{:?}", e)),
@@ -115,13 +132,20 @@ pub fn init_backend(init_msg: &[u8]) -> std::result::Result<Backend, String> {
 }
 
 impl Backend {
-    pub fn new(col_path: &str, media_folder: &str, media_db: &str, i18n: I18n) -> Result<Backend> {
+    pub fn new(
+        col_path: &str,
+        media_folder: &str,
+        media_db: &str,
+        i18n: I18n,
+        log: Logger,
+    ) -> Result<Backend> {
         Ok(Backend {
             col_path: col_path.into(),
             media_folder: media_folder.into(),
             media_db: media_db.into(),
             progress_callback: None,
             i18n,
+            log,
         })
     }
 
@@ -372,7 +396,7 @@ impl Backend {
         };
 
         let mut rt = Runtime::new().unwrap();
-        rt.block_on(mgr.sync_media(callback, &input.endpoint, &input.hkey))
+        rt.block_on(mgr.sync_media(callback, &input.endpoint, &input.hkey, self.log.clone()))
     }
 
     fn check_media(&self) -> Result<pb::MediaCheckOut> {
@@ -380,7 +404,7 @@ impl Backend {
             |progress: usize| self.fire_progress_callback(Progress::MediaCheck(progress as u32));
 
         let mgr = MediaManager::new(&self.media_folder, &self.media_db)?;
-        let mut checker = MediaChecker::new(&mgr, &self.col_path, callback, &self.i18n);
+        let mut checker = MediaChecker::new(&mgr, &self.col_path, callback, &self.i18n, &self.log);
         let mut output = checker.check()?;
 
         let report = checker.summarize_output(&mut output);
@@ -515,7 +539,9 @@ pub fn init_i18n_backend(init_msg: &[u8]) -> Result<I18nBackend> {
         Err(_) => return Err(AnkiError::invalid_input("couldn't decode init msg")),
     };
 
-    let i18n = I18n::new(&input.preferred_langs, input.locale_folder_path);
+    let log = log::terminal();
+
+    let i18n = I18n::new(&input.preferred_langs, input.locale_folder_path, log);
 
     Ok(I18nBackend { i18n })
 }
diff --git a/rslib/src/i18n/mod.rs b/rslib/src/i18n/mod.rs
index 4f6c4626c..e35f69e1b 100644
--- a/rslib/src/i18n/mod.rs
+++ b/rslib/src/i18n/mod.rs
@@ -2,9 +2,9 @@
 // License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 
 use crate::err::Result;
+use crate::log::{error, Logger};
 use fluent::{FluentArgs, FluentBundle, FluentResource, FluentValue};
 use intl_memoizer::IntlLangMemoizer;
-use log::error;
 use num_format::Locale;
 use std::borrow::Cow;
 use std::fs;
@@ -167,10 +167,11 @@ fn get_bundle(
     text: String,
     extra_text: String,
     locales: &[LanguageIdentifier],
+    log: &Logger,
 ) -> Option<FluentBundle<FluentResource>> {
     let res = FluentResource::try_new(text)
         .map_err(|e| {
-            error!("Unable to parse translations file: {:?}", e);
+            error!(log, "Unable to parse translations file: {:?}", e);
         })
         .ok()?;
 
@@ -178,14 +179,14 @@ fn get_bundle(
     bundle
         .add_resource(res)
         .map_err(|e| {
-            error!("Duplicate key detected in translation file: {:?}", e);
+            error!(log, "Duplicate key detected in translation file: {:?}", e);
         })
         .ok()?;
 
     if !extra_text.is_empty() {
         match FluentResource::try_new(extra_text) {
             Ok(res) => bundle.add_resource_overriding(res),
-            Err((_res, e)) => error!("Unable to parse translations file: {:?}", e),
+            Err((_res, e)) => error!(log, "Unable to parse translations file: {:?}", e),
         }
     }
 
@@ -206,12 +207,13 @@ fn get_bundle_with_extra(
     lang: Option<&LanguageIdentifier>,
     ftl_folder: &Path,
     locales: &[LanguageIdentifier],
+    log: &Logger,
 ) -> Option<FluentBundle<FluentResource>> {
     let extra_text = if let Some(path) = lang_folder(lang, &ftl_folder) {
         match ftl_external_text(&path) {
             Ok(text) => text,
             Err(e) => {
-                error!("Error reading external FTL files: {:?}", e);
+                error!(log, "Error reading external FTL files: {:?}", e);
                 "".into()
             }
         }
@@ -219,16 +221,21 @@ fn get_bundle_with_extra(
         "".into()
     };
 
-    get_bundle(text, extra_text, locales)
+    get_bundle(text, extra_text, locales, log)
 }
 
 #[derive(Clone)]
 pub struct I18n {
     inner: Arc<Mutex<I18nInner>>,
+    log: Logger,
 }
 
 impl I18n {
-    pub fn new<S: AsRef<str>, P: Into<PathBuf>>(locale_codes: &[S], ftl_folder: P) -> Self {
+    pub fn new<S: AsRef<str>, P: Into<PathBuf>>(
+        locale_codes: &[S],
+        ftl_folder: P,
+        log: Logger,
+    ) -> Self {
         let ftl_folder = ftl_folder.into();
 
         let mut langs = vec![];
@@ -246,10 +253,12 @@ impl I18n {
         for lang in &langs {
             // if the language is bundled in the binary
             if let Some(text) = ftl_localized_text(lang) {
-                if let Some(bundle) = get_bundle_with_extra(text, Some(lang), &ftl_folder, &langs) {
+                if let Some(bundle) =
+                    get_bundle_with_extra(text, Some(lang), &ftl_folder, &langs, &log)
+                {
                     bundles.push(bundle);
                 } else {
-                    error!("Failed to create bundle for {:?}", lang.language())
+                    error!(log, "Failed to create bundle for {:?}", lang.language())
                 }
 
                 // if English was listed, any further preferences are skipped,
@@ -265,11 +274,12 @@ impl I18n {
 
         // add English templates
         let template_bundle =
-            get_bundle_with_extra(ftl_template_text(), None, &ftl_folder, &langs).unwrap();
+            get_bundle_with_extra(ftl_template_text(), None, &ftl_folder, &langs, &log).unwrap();
         bundles.push(template_bundle);
 
         Self {
             inner: Arc::new(Mutex::new(I18nInner { bundles })),
+            log,
         }
     }
 
@@ -302,7 +312,7 @@ impl I18n {
             let mut errs = vec![];
             let out = bundle.format_pattern(pat, args.as_ref(), &mut errs);
             if !errs.is_empty() {
-                error!("Error(s) in translation '{}': {:?}", key, errs);
+                error!(self.log, "Error(s) in translation '{}': {:?}", key, errs);
             }
             // clone so we can discard args
             return out.to_string().into();
@@ -389,6 +399,7 @@ impl NumberFormatter {
 mod test {
     use crate::i18n::NumberFormatter;
     use crate::i18n::{tr_args, I18n};
+    use crate::log;
     use std::path::PathBuf;
     use unic_langid::langid;
 
@@ -403,8 +414,10 @@ mod test {
         let mut ftl_dir = PathBuf::from(env!("CARGO_MANIFEST_DIR"));
         ftl_dir.push("tests/support/ftl");
 
+        let log = log::terminal();
+
         // English template
-        let i18n = I18n::new(&["zz"], &ftl_dir);
+        let i18n = I18n::new(&["zz"], &ftl_dir, log.clone());
         assert_eq!(i18n.tr_("valid-key", None), "a valid key");
         assert_eq!(i18n.tr_("invalid-key", None), "invalid-key");
 
@@ -427,7 +440,7 @@ mod test {
         );
 
         // Another language
-        let i18n = I18n::new(&["ja_JP"], &ftl_dir);
+        let i18n = I18n::new(&["ja_JP"], &ftl_dir, log.clone());
         assert_eq!(i18n.tr_("valid-key", None), "キー");
         assert_eq!(i18n.tr_("only-in-english", None), "not translated");
         assert_eq!(i18n.tr_("invalid-key", None), "invalid-key");
@@ -438,7 +451,7 @@ mod test {
         );
 
         // Decimal separator
-        let i18n = I18n::new(&["pl-PL"], &ftl_dir);
+        let i18n = I18n::new(&["pl-PL"], &ftl_dir, log.clone());
         // falls back on English, but with Polish separators
         assert_eq!(
             i18n.tr_("two-args-key", Some(tr_args!["one"=>1, "two"=>2.07])),
diff --git a/rslib/src/lib.rs b/rslib/src/lib.rs
index 936394e62..cce95c5b0 100644
--- a/rslib/src/lib.rs
+++ b/rslib/src/lib.rs
@@ -14,6 +14,7 @@ pub mod cloze;
 pub mod err;
 pub mod i18n;
 pub mod latex;
+pub mod log;
 pub mod media;
 pub mod sched;
 pub mod template;
diff --git a/rslib/src/log.rs b/rslib/src/log.rs
new file mode 100644
index 000000000..497608619
--- /dev/null
+++ b/rslib/src/log.rs
@@ -0,0 +1,43 @@
+// Copyright: Ankitects Pty Ltd and contributors
+// License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
+
+pub use slog::{debug, error, Logger};
+use slog::{slog_o, Drain};
+use slog_async::OverflowStrategy;
+use std::fs::OpenOptions;
+use std::io;
+use std::path::Path;
+
+pub(crate) fn terminal() -> Logger {
+    let decorator = slog_term::TermDecorator::new().build();
+    let drain = slog_term::FullFormat::new(decorator).build().fuse();
+    let drain = slog_envlogger::new(drain);
+    let drain = slog_async::Async::new(drain)
+        .chan_size(1_024)
+        .overflow_strategy(OverflowStrategy::Block)
+        .build()
+        .fuse();
+    Logger::root(drain, slog_o!())
+}
+
+fn file(path: &Path) -> io::Result<Logger> {
+    let file = OpenOptions::new().create(true).append(true).open(path)?;
+
+    let decorator = slog_term::PlainSyncDecorator::new(file);
+    let drain = slog_term::FullFormat::new(decorator).build().fuse();
+    let drain = slog_envlogger::new(drain);
+    let drain = slog_async::Async::new(drain)
+        .chan_size(1_024)
+        .overflow_strategy(OverflowStrategy::Block)
+        .build()
+        .fuse();
+    Ok(Logger::root(drain, slog_o!()))
+}
+
+/// Get a logger, logging to a file if a path was provided, otherwise terminal.
+pub(crate) fn default_logger(path: Option<&Path>) -> io::Result<Logger> {
+    Ok(match path {
+        Some(path) => file(path)?,
+        None => terminal(),
+    })
+}
diff --git a/rslib/src/media/changetracker.rs b/rslib/src/media/changetracker.rs
index 555a80453..d931c4563 100644
--- a/rslib/src/media/changetracker.rs
+++ b/rslib/src/media/changetracker.rs
@@ -2,6 +2,7 @@
 // License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 
 use crate::err::{AnkiError, Result};
+use crate::log::{debug, Logger};
 use crate::media::database::{MediaDatabaseContext, MediaEntry};
 use crate::media::files::{
     filename_if_normalized, mtime_as_i64, sha1_of_file, MEDIA_SYNC_FILESIZE_LIMIT,
@@ -25,17 +26,23 @@ where
     media_folder: &'a Path,
     progress_cb: F,
     checked: usize,
+    log: &'a Logger,
 }
 
 impl<F> ChangeTracker<'_, F>
 where
     F: FnMut(usize) -> bool,
 {
-    pub(super) fn new(media_folder: &Path, progress: F) -> ChangeTracker<F> {
+    pub(super) fn new<'a>(
+        media_folder: &'a Path,
+        progress: F,
+        log: &'a Logger,
+    ) -> ChangeTracker<'a, F> {
         ChangeTracker {
             media_folder,
             progress_cb: progress,
             checked: 0,
+            log,
         }
     }
 
@@ -53,7 +60,9 @@ where
             let dirmod = mtime_as_i64(self.media_folder)?;
 
             let mut meta = ctx.get_meta()?;
+            debug!(self.log, "begin change check"; "folder_mod" => dirmod, "db_mod" => meta.folder_mtime);
             if dirmod == meta.folder_mtime {
+                debug!(self.log, "skip check");
                 return Ok(());
             } else {
                 meta.folder_mtime = dirmod;
@@ -106,6 +115,7 @@ where
                 Some(fname) => fname,
                 None => {
                     // not normalized; skip it
+                    debug!(self.log, "ignore non-normalized"; "fname"=>disk_fname);
                     continue;
                 }
             };
@@ -135,6 +145,7 @@ where
                 .as_secs() as i64;
             if let Some(previous_mtime) = previous_mtime {
                 if previous_mtime == mtime {
+                    debug!(self.log, "mtime unchanged"; "fname"=>fname.as_ref());
                     continue;
                 }
             }
@@ -147,6 +158,10 @@ where
                 mtime,
                 is_new: previous_mtime.is_none(),
             });
+            debug!(self.log, "added or changed";
+                "fname"=>fname.as_ref(),
+                "mtime"=>mtime,
+                "sha1"=>sha1.as_ref().map(|s| hex::encode(&s[0..4])));
 
             self.checked += 1;
             if self.checked % 10 == 0 {
@@ -156,6 +171,9 @@ where
 
         // any remaining entries from the database have been deleted
         let removed: Vec<_> = mtimes.into_iter().map(|(k, _)| k).collect();
+        for f in &removed {
+            debug!(self.log, "db entry missing on disk"; "fname"=>f);
+        }
 
         Ok((added_or_changed, removed))
     }
@@ -264,7 +282,9 @@ mod test {
 
         let progress_cb = |_n| true;
 
-        ChangeTracker::new(&mgr.media_folder, progress_cb).register_changes(&mut ctx)?;
+        let log = crate::log::terminal();
+
+        ChangeTracker::new(&mgr.media_folder, progress_cb, &log).register_changes(&mut ctx)?;
 
         let mut entry = ctx.transact(|ctx| {
             assert_eq!(ctx.count()?, 1);
@@ -299,7 +319,7 @@ mod test {
             Ok(entry)
         })?;
 
-        ChangeTracker::new(&mgr.media_folder, progress_cb).register_changes(&mut ctx)?;
+        ChangeTracker::new(&mgr.media_folder, progress_cb, &log).register_changes(&mut ctx)?;
 
         ctx.transact(|ctx| {
             assert_eq!(ctx.count()?, 1);
@@ -332,7 +352,7 @@ mod test {
 
         change_mtime(&media_dir);
 
-        ChangeTracker::new(&mgr.media_folder, progress_cb).register_changes(&mut ctx)?;
+        ChangeTracker::new(&mgr.media_folder, progress_cb, &log).register_changes(&mut ctx)?;
 
         assert_eq!(ctx.count()?, 0);
         assert!(!ctx.get_pending_uploads(1)?.is_empty());
diff --git a/rslib/src/media/check.rs b/rslib/src/media/check.rs
index caf64728b..44aea31d0 100644
--- a/rslib/src/media/check.rs
+++ b/rslib/src/media/check.rs
@@ -4,6 +4,7 @@
 use crate::err::{AnkiError, Result};
 use crate::i18n::{tr_args, tr_strs, FString, I18n};
 use crate::latex::extract_latex_expanding_clozes;
+use crate::log::{debug, Logger};
 use crate::media::col::{
     for_every_note, get_note_types, mark_collection_modified, open_or_create_collection_db,
     set_note, Note,
@@ -15,7 +16,6 @@ use crate::media::files::{
 use crate::text::{normalize_to_nfc, MediaRef};
 use crate::{media::MediaManager, text::extract_media_refs};
 use coarsetime::Instant;
-use log::debug;
 use std::collections::{HashMap, HashSet};
 use std::path::Path;
 use std::{borrow::Cow, fs, time};
@@ -47,6 +47,7 @@ where
     checked: usize,
     progress_updated: Instant,
     i18n: &'a I18n,
+    log: &'a Logger,
 }
 
 impl<P> MediaChecker<'_, P>
@@ -58,6 +59,7 @@ where
         col_path: &'a Path,
         progress_cb: P,
         i18n: &'a I18n,
+        log: &'a Logger,
     ) -> MediaChecker<'a, P> {
         MediaChecker {
             mgr,
@@ -66,6 +68,7 @@ where
             checked: 0,
             progress_updated: Instant::now(),
             i18n,
+            log,
         }
     }
 
@@ -258,7 +261,7 @@ where
             }
         })?;
         let fname = self.mgr.add_file(ctx, disk_fname, &data)?;
-        debug!("renamed {} to {}", disk_fname, fname);
+        debug!(self.log, "renamed"; "from"=>disk_fname, "to"=>&fname.as_ref());
         assert_ne!(fname.as_ref(), disk_fname);
 
         // move the originally named file to the trash
@@ -303,6 +306,7 @@ where
                 .unwrap_or(0);
             if elap_secs >= 7 * 86_400 {
                 debug!(
+                    self.log,
                     "removing {:?} from trash, as 7 days have elapsed",
                     dentry.path()
                 );
@@ -439,13 +443,15 @@ fn extract_latex_refs(note: &Note, seen_files: &mut HashSet<String>, svg: bool)
 mod test {
     use crate::err::Result;
     use crate::i18n::I18n;
+    use crate::log;
+    use crate::log::Logger;
     use crate::media::check::{MediaCheckOutput, MediaChecker};
     use crate::media::MediaManager;
     use std::fs;
     use std::path::PathBuf;
     use tempfile::{tempdir, TempDir};
 
-    fn common_setup() -> Result<(TempDir, MediaManager, PathBuf)> {
+    fn common_setup() -> Result<(TempDir, MediaManager, PathBuf, Logger)> {
         let dir = tempdir()?;
         let media_dir = dir.path().join("media");
         fs::create_dir(&media_dir)?;
@@ -458,12 +464,13 @@ mod test {
 
         let mgr = MediaManager::new(&media_dir, media_db)?;
 
-        Ok((dir, mgr, col_path))
+        let log = log::terminal();
+        Ok((dir, mgr, col_path, log))
     }
 
     #[test]
     fn media_check() -> Result<()> {
-        let (_dir, mgr, col_path) = common_setup()?;
+        let (_dir, mgr, col_path, log) = common_setup()?;
 
         // add some test files
         fs::write(&mgr.media_folder.join("zerobytes"), "")?;
@@ -473,10 +480,10 @@ mod test {
         fs::write(&mgr.media_folder.join("_under.jpg"), "foo")?;
         fs::write(&mgr.media_folder.join("unused.jpg"), "foo")?;
 
-        let i18n = I18n::new(&["zz"], "dummy");
+        let i18n = I18n::new(&["zz"], "dummy", log.clone());
 
         let progress = |_n| true;
-        let mut checker = MediaChecker::new(&mgr, &col_path, progress, &i18n);
+        let mut checker = MediaChecker::new(&mgr, &col_path, progress, &i18n, &log);
         let mut output = checker.check()?;
 
         assert_eq!(
@@ -522,14 +529,14 @@ Unused: unused.jpg
 
     #[test]
     fn unicode_normalization() -> Result<()> {
-        let (_dir, mgr, col_path) = common_setup()?;
+        let (_dir, mgr, col_path, log) = common_setup()?;
 
-        let i18n = I18n::new(&["zz"], "dummy");
+        let i18n = I18n::new(&["zz"], "dummy", log.clone());
 
         fs::write(&mgr.media_folder.join("ぱぱ.jpg"), "nfd encoding")?;
 
         let progress = |_n| true;
-        let mut checker = MediaChecker::new(&mgr, &col_path, progress, &i18n);
+        let mut checker = MediaChecker::new(&mgr, &col_path, progress, &i18n, &log);
         let mut output = checker.check()?;
         output.missing.sort();
 
diff --git a/rslib/src/media/database.rs b/rslib/src/media/database.rs
index 480bb790b..f924f21df 100644
--- a/rslib/src/media/database.rs
+++ b/rslib/src/media/database.rs
@@ -2,13 +2,12 @@
 // License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 
 use crate::err::Result;
-use log::debug;
 use rusqlite::{params, Connection, OptionalExtension, Row, Statement, NO_PARAMS};
 use std::collections::HashMap;
 use std::path::Path;
 
 fn trace(s: &str) {
-    debug!("sql: {}", s)
+    println!("sql: {}", s)
 }
 
 pub(super) fn open_or_create<P: AsRef<Path>>(path: P) -> Result<Connection> {
diff --git a/rslib/src/media/files.rs b/rslib/src/media/files.rs
index 870f25287..88df22234 100644
--- a/rslib/src/media/files.rs
+++ b/rslib/src/media/files.rs
@@ -2,8 +2,8 @@
 // License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 
 use crate::err::Result;
+use crate::log::{debug, Logger};
 use lazy_static::lazy_static;
-use log::debug;
 use regex::Regex;
 use sha1::Sha1;
 use std::borrow::Cow;
@@ -364,6 +364,7 @@ pub(super) fn add_file_from_ankiweb(
     media_folder: &Path,
     fname: &str,
     data: &[u8],
+    log: &Logger,
 ) -> Result<AddedFile> {
     let sha1 = sha1_of_data(data);
     let normalized = normalize_filename(fname);
@@ -374,7 +375,7 @@ pub(super) fn add_file_from_ankiweb(
         fs::write(&path, data)?;
         (None, path)
     } else {
-        debug!("non-normalized filename received {}", fname);
+        debug!(log, "non-normalized filename received"; "fname"=>&fname);
         // ankiweb sent us a non-normalized filename, so we'll rename it
         let new_name = add_data_to_folder_uniquely(media_folder, fname, data, sha1)?;
         (
diff --git a/rslib/src/media/mod.rs b/rslib/src/media/mod.rs
index 1ed5d52f2..c0dcfcca8 100644
--- a/rslib/src/media/mod.rs
+++ b/rslib/src/media/mod.rs
@@ -6,6 +6,7 @@ use crate::media::database::{open_or_create, MediaDatabaseContext, MediaEntry};
 use crate::media::files::{add_data_to_folder_uniquely, mtime_as_i64, remove_files, sha1_of_data};
 use crate::media::sync::{MediaSyncProgress, MediaSyncer};
 use rusqlite::Connection;
+use slog::Logger;
 use std::borrow::Cow;
 use std::path::{Path, PathBuf};
 
diff --git a/rslib/src/media/sync.rs b/rslib/src/media/sync.rs
index c8efe5c87..c6cc551d5 100644
--- a/rslib/src/media/sync.rs
+++ b/rslib/src/media/sync.rs
@@ -11,10 +11,10 @@ use crate::media::MediaManager;
 use crate::version;
 use bytes::Bytes;
 use coarsetime::Instant;
-use log::debug;
 use reqwest::{multipart, Client, Response};
 use serde_derive::{Deserialize, Serialize};
 use serde_tuple::Serialize_tuple;
+use slog::{debug, Logger};
 use std::borrow::Cow;
 use std::collections::HashMap;
 use std::io::{Read, Write};
@@ -46,6 +46,7 @@ where
     progress: MediaSyncProgress,
     progress_updated: Instant,
     endpoint: &'a str,
+    log: Logger,
 }
 
 #[derive(Debug, Deserialize)]
@@ -135,7 +136,12 @@ impl<P> MediaSyncer<'_, P>
 where
     P: Fn(&MediaSyncProgress) -> bool,
 {
-    pub fn new<'a>(mgr: &'a MediaManager, progress_cb: P, endpoint: &'a str) -> MediaSyncer<'a, P> {
+    pub fn new<'a>(
+        mgr: &'a MediaManager,
+        progress_cb: P,
+        endpoint: &'a str,
+        log: Logger,
+    ) -> MediaSyncer<'a, P> {
         let client = Client::builder()
             .connect_timeout(time::Duration::from_secs(30))
             .build()
@@ -151,6 +157,7 @@ where
             progress: Default::default(),
             progress_updated: Instant::now(),
             endpoint,
+            log,
         }
     }
 
@@ -165,16 +172,19 @@ where
         let meta = self.ctx.get_meta()?;
         let client_usn = meta.last_sync_usn;
 
-        debug!("beginning media sync");
+        debug!(self.log, "begin media sync");
         let (sync_key, server_usn) = self.sync_begin(hkey).await?;
         self.skey = Some(sync_key);
-        debug!("server usn was {}", server_usn);
+        debug!(self.log, "server usn was {}", server_usn);
 
         let mut actions_performed = false;
 
         // need to fetch changes from server?
         if client_usn != server_usn {
-            debug!("differs from local usn {}, fetching changes", client_usn);
+            debug!(
+                self.log,
+                "differs from local usn {}, fetching changes", client_usn
+            );
             self.fetch_changes(meta).await?;
             actions_performed = true;
         }
@@ -192,7 +202,7 @@ where
 
         self.fire_progress_cb()?;
 
-        debug!("media sync complete");
+        debug!(self.log, "media sync complete");
 
         Ok(())
     }
@@ -215,7 +225,7 @@ where
             }
         };
 
-        ChangeTracker::new(self.mgr.media_folder.as_path(), progress)
+        ChangeTracker::new(self.mgr.media_folder.as_path(), progress, &self.log)
             .register_changes(&mut self.ctx)
     }
 
@@ -242,11 +252,15 @@ where
     async fn fetch_changes(&mut self, mut meta: MediaDatabaseMetadata) -> Result<()> {
         let mut last_usn = meta.last_sync_usn;
         loop {
-            debug!("fetching record batch starting from usn {}", last_usn);
+            debug!(
+                self.log,
+                "fetching record batch";
+                 "start_usn"=>last_usn
+            );
 
             let batch = self.fetch_record_batch(last_usn).await?;
             if batch.is_empty() {
-                debug!("empty batch, done");
+                debug!(self.log, "empty batch, done");
                 break;
             }
             last_usn = batch.last().unwrap().usn;
@@ -255,7 +269,7 @@ where
             self.maybe_fire_progress_cb()?;
 
             let (to_download, to_delete, to_remove_pending) =
-                determine_required_changes(&mut self.ctx, &batch)?;
+                determine_required_changes(&mut self.ctx, &batch, &self.log)?;
 
             // file removal
             self.mgr.remove_files(&mut self.ctx, to_delete.as_slice())?;
@@ -272,9 +286,12 @@ where
                     .map(ToOwned::to_owned)
                     .collect();
                 let zip_data = self.fetch_zip(batch.as_slice()).await?;
-                let download_batch =
-                    extract_into_media_folder(self.mgr.media_folder.as_path(), zip_data)?
-                        .into_iter();
+                let download_batch = extract_into_media_folder(
+                    self.mgr.media_folder.as_path(),
+                    zip_data,
+                    &self.log,
+                )?
+                .into_iter();
                 let len = download_batch.len();
                 dl_fnames = &dl_fnames[len..];
                 downloaded.extend(download_batch);
@@ -285,10 +302,11 @@ where
 
             // then update the DB
             let dirmod = mtime_as_i64(&self.mgr.media_folder)?;
+            let log = &self.log;
             self.ctx.transact(|ctx| {
-                record_clean(ctx, &to_remove_pending)?;
-                record_removals(ctx, &to_delete)?;
-                record_additions(ctx, downloaded)?;
+                record_clean(ctx, &to_remove_pending, log)?;
+                record_removals(ctx, &to_delete, log)?;
+                record_additions(ctx, downloaded, log)?;
 
                 // update usn
                 meta.last_sync_usn = last_usn;
@@ -308,7 +326,7 @@ where
                 break;
             }
 
-            let zip_data = zip_files(&mut self.ctx, &self.mgr.media_folder, &pending)?;
+            let zip_data = zip_files(&mut self.ctx, &self.mgr.media_folder, &pending, &self.log)?;
             if zip_data.is_none() {
                 self.progress.checked += pending.len();
                 self.maybe_fire_progress_cb()?;
@@ -334,14 +352,16 @@ where
                 .map(|e| &e.fname)
                 .collect();
             let fname_cnt = fnames.len() as i32;
+            let log = &self.log;
             self.ctx.transact(|ctx| {
-                record_clean(ctx, fnames.as_slice())?;
+                record_clean(ctx, fnames.as_slice(), log)?;
                 let mut meta = ctx.get_meta()?;
                 if meta.last_sync_usn + fname_cnt == reply.current_usn {
                     meta.last_sync_usn = reply.current_usn;
                     ctx.set_meta(&meta)?;
                 } else {
                     debug!(
+                        log,
                         "server usn {} is not {}, skipping usn update",
                         reply.current_usn,
                         meta.last_sync_usn + fname_cnt
@@ -411,7 +431,7 @@ where
     async fn fetch_zip(&self, files: &[&String]) -> Result<Bytes> {
         let url = format!("{}downloadFiles", self.endpoint);
 
-        debug!("requesting files: {:?}", files);
+        debug!(self.log, "requesting files: {:?}", files);
 
         let req = ZipRequest { files };
         let resp = ankiweb_json_request(&self.client, &url, &req, self.skey()).await?;
@@ -470,6 +490,7 @@ fn determine_required_change(
 fn determine_required_changes<'a>(
     ctx: &mut MediaDatabaseContext,
     records: &'a [ServerMediaRecord],
+    log: &Logger,
 ) -> Result<(Vec<&'a String>, Vec<&'a String>, Vec<&'a String>)> {
     let mut to_download = vec![];
     let mut to_delete = vec![];
@@ -493,12 +514,13 @@ fn determine_required_changes<'a>(
 
         let req_change = determine_required_change(&local_sha1, &remote.sha1, local_state);
         debug!(
-            "for {}, lsha={} rsha={} lstate={:?} -> {:?}",
-            remote.fname,
-            local_sha1.chars().take(8).collect::<String>(),
-            remote.sha1.chars().take(8).collect::<String>(),
-            local_state,
-            req_change
+            log,
+            "determine action";
+            "fname" => &remote.fname,
+            "lsha" => local_sha1.chars().take(8).collect::<String>(),
+            "rsha" => remote.sha1.chars().take(8).collect::<String>(),
+            "state" => ?local_state,
+            "action" => ?req_change
         );
         match req_change {
             RequiredChange::Download => to_download.push(&remote.fname),
@@ -556,7 +578,11 @@ async fn ankiweb_request(
         .map_err(Into::into)
 }
 
-fn extract_into_media_folder(media_folder: &Path, zip: Bytes) -> Result<Vec<AddedFile>> {
+fn extract_into_media_folder(
+    media_folder: &Path,
+    zip: Bytes,
+    log: &Logger,
+) -> Result<Vec<AddedFile>> {
     let reader = io::Cursor::new(zip);
     let mut zip = zip::ZipArchive::new(reader)?;
 
@@ -578,9 +604,9 @@ fn extract_into_media_folder(media_folder: &Path, zip: Bytes) -> Result<Vec<Adde
         let mut data = Vec::with_capacity(file.size() as usize);
         file.read_to_end(&mut data)?;
 
-        debug!("writing {}", real_name);
+        debug!(log, "write"; "fname" => real_name);
 
-        let added = add_file_from_ankiweb(media_folder, real_name, &data)?;
+        let added = add_file_from_ankiweb(media_folder, real_name, &data, log)?;
 
         output.push(added);
     }
@@ -588,21 +614,29 @@ fn extract_into_media_folder(media_folder: &Path, zip: Bytes) -> Result<Vec<Adde
     Ok(output)
 }
 
-fn record_removals(ctx: &mut MediaDatabaseContext, removals: &[&String]) -> Result<()> {
+fn record_removals(
+    ctx: &mut MediaDatabaseContext,
+    removals: &[&String],
+    log: &Logger,
+) -> Result<()> {
     for &fname in removals {
-        debug!("marking removed: {}", fname);
+        debug!(log, "mark removed"; "fname" => fname);
         ctx.remove_entry(fname)?;
     }
 
     Ok(())
 }
 
-fn record_additions(ctx: &mut MediaDatabaseContext, additions: Vec<AddedFile>) -> Result<()> {
+fn record_additions(
+    ctx: &mut MediaDatabaseContext,
+    additions: Vec<AddedFile>,
+    log: &Logger,
+) -> Result<()> {
     for file in additions {
         if let Some(renamed) = file.renamed_from {
             // the file AnkiWeb sent us wasn't normalized, so we need to record
             // the old file name as a deletion
-            debug!("marking non-normalized file as deleted: {}", renamed);
+            debug!(log, "marking non-normalized file as deleted: {}", renamed);
             let mut entry = MediaEntry {
                 fname: renamed,
                 sha1: None,
@@ -611,7 +645,10 @@ fn record_additions(ctx: &mut MediaDatabaseContext, additions: Vec<AddedFile>) -
             };
             ctx.set_entry(&entry)?;
             // and upload the new filename to ankiweb
-            debug!("marking renamed file as needing upload: {}", file.fname);
+            debug!(
+                log,
+                "marking renamed file as needing upload: {}", file.fname
+            );
             entry = MediaEntry {
                 fname: file.fname.to_string(),
                 sha1: Some(file.sha1),
@@ -627,10 +664,9 @@ fn record_additions(ctx: &mut MediaDatabaseContext, additions: Vec<AddedFile>) -
                 mtime: file.mtime,
                 sync_required: false,
             };
-            debug!(
-                "marking added: {} {}",
-                entry.fname,
-                hex::encode(entry.sha1.as_ref().unwrap())
+            debug!(log, "mark added";
+                "fname" => &entry.fname,
+                "sha1" => hex::encode(&entry.sha1.as_ref().unwrap()[0..4])
             );
             ctx.set_entry(&entry)?;
         }
@@ -639,12 +675,12 @@ fn record_additions(ctx: &mut MediaDatabaseContext, additions: Vec<AddedFile>) -
     Ok(())
 }
 
-fn record_clean(ctx: &mut MediaDatabaseContext, clean: &[&String]) -> Result<()> {
+fn record_clean(ctx: &mut MediaDatabaseContext, clean: &[&String], log: &Logger) -> Result<()> {
     for &fname in clean {
         if let Some(mut entry) = ctx.get_entry(fname)? {
             if entry.sync_required {
                 entry.sync_required = false;
-                debug!("marking clean: {}", entry.fname);
+                debug!(log, "mark clean"; "fname"=>&entry.fname);
                 ctx.set_entry(&entry)?;
             }
         }
@@ -657,6 +693,7 @@ fn zip_files<'a>(
     ctx: &mut MediaDatabaseContext,
     media_folder: &Path,
     files: &'a [MediaEntry],
+    log: &Logger,
 ) -> Result<Option<Vec<u8>>> {
     let buf = vec![];
     let mut invalid_entries = vec![];
@@ -678,7 +715,7 @@ fn zip_files<'a>(
         let file_data = match data_for_file(media_folder, &file.fname) {
             Ok(data) => data,
             Err(e) => {
-                debug!("error accessing {}: {}", &file.fname, e);
+                debug!(log, "error accessing {}: {}", &file.fname, e);
                 invalid_entries.push(&file.fname);
                 continue;
             }
@@ -687,7 +724,7 @@ fn zip_files<'a>(
         if let Some(data) = &file_data {
             let normalized = normalize_filename(&file.fname);
             if let Cow::Owned(o) = normalized {
-                debug!("media check required: {} should be {}", &file.fname, o);
+                debug!(log, "media check required: {} should be {}", &file.fname, o);
                 invalid_entries.push(&file.fname);
                 continue;
             }
@@ -706,9 +743,10 @@ fn zip_files<'a>(
         }
 
         debug!(
-            "will upload {} as {}",
-            file.fname,
-            if file_data.is_some() {
+            log,
+            "will upload";
+             "fname"=>&file.fname,
+             "kind"=>if file_data.is_some() {
                 "addition "
             } else {
                 "removal"
@@ -772,8 +810,10 @@ mod test {
             true
         };
 
+        let log = crate::log::terminal();
+
         let mgr = MediaManager::new(&media_dir, &media_db)?;
-        mgr.sync_media(progress, "https://sync.ankiweb.net/msync/", hkey)
+        mgr.sync_media(progress, "https://sync.ankiweb.net/msync/", hkey, log)
             .await?;
 
         Ok(())
@@ -781,8 +821,6 @@ mod test {
 
     #[test]
     fn sync() {
-        env_logger::init();
-
         let hkey = match std::env::var("TEST_HKEY") {
             Ok(s) => s,
             Err(_) => {
diff --git a/rslib/src/sched/timespan.rs b/rslib/src/sched/timespan.rs
index a984a2a2b..660de5b93 100644
--- a/rslib/src/sched/timespan.rs
+++ b/rslib/src/sched/timespan.rs
@@ -176,13 +176,15 @@ impl Timespan {
 #[cfg(test)]
 mod test {
     use crate::i18n::I18n;
+    use crate::log;
     use crate::sched::timespan::{
         answer_button_time, learning_congrats, studied_today, time_span, MONTH,
     };
 
     #[test]
     fn answer_buttons() {
-        let i18n = I18n::new(&["zz"], "");
+        let log = log::terminal();
+        let i18n = I18n::new(&["zz"], "", log);
         assert_eq!(answer_button_time(30.0, &i18n), "30s");
         assert_eq!(answer_button_time(70.0, &i18n), "1.2m");
         assert_eq!(answer_button_time(1.1 * MONTH, &i18n), "1.1mo");
@@ -190,7 +192,8 @@ mod test {
 
     #[test]
     fn time_spans() {
-        let i18n = I18n::new(&["zz"], "");
+        let log = log::terminal();
+        let i18n = I18n::new(&["zz"], "", log);
         assert_eq!(time_span(1.0, &i18n, false), "1 second");
         assert_eq!(time_span(30.3, &i18n, false), "30 seconds");
         assert_eq!(time_span(30.3, &i18n, true), "30.3 seconds");
@@ -202,7 +205,8 @@ mod test {
     #[test]
     fn combo() {
         // temporary test of fluent term handling
-        let i18n = I18n::new(&["zz"], "");
+        let log = log::terminal();
+        let i18n = I18n::new(&["zz"], "", log);
         assert_eq!(
             &studied_today(3, 13.0, &i18n).replace("\n", " "),
             "Studied 3 cards in 13 seconds today (4.33s/card)"
diff --git a/rspy/Cargo.toml b/rspy/Cargo.toml
index 46e17ddc2..e06242f68 100644
--- a/rspy/Cargo.toml
+++ b/rspy/Cargo.toml
@@ -6,8 +6,6 @@ authors = ["Ankitects Pty Ltd and contributors"]
 
 [dependencies]
 anki = { path = "../rslib" }
-log = "0.4.8"
-env_logger = "0.7.1"
 tokio = "0.2.11"
 
 [dependencies.pyo3]
diff --git a/rspy/src/lib.rs b/rspy/src/lib.rs
index 45e705fea..f24fccc76 100644
--- a/rspy/src/lib.rs
+++ b/rspy/src/lib.rs
@@ -4,7 +4,6 @@
 use anki::backend::{
     init_backend, init_i18n_backend, Backend as RustBackend, I18nBackend as RustI18nBackend,
 };
-use log::error;
 use pyo3::prelude::*;
 use pyo3::types::PyBytes;
 use pyo3::{exceptions, wrap_pyfunction};
@@ -55,7 +54,7 @@ impl Backend {
                 let res: PyObject = match callback.call1(py, (out_obj,)) {
                     Ok(res) => res,
                     Err(e) => {
-                        error!("error calling callback:");
+                        println!("error calling callback:");
                         e.print(py);
                         return false;
                     }
@@ -63,7 +62,7 @@ impl Backend {
                 match res.extract(py) {
                     Ok(cont) => cont,
                     Err(e) => {
-                        error!("callback did not return bool: {:?}", e);
+                        println!("callback did not return bool: {:?}", e);
                         return false;
                     }
                 }
@@ -107,7 +106,5 @@ fn ankirspy(_py: Python, m: &PyModule) -> PyResult<()> {
     m.add_wrapped(wrap_pyfunction!(open_backend)).unwrap();
     m.add_wrapped(wrap_pyfunction!(open_i18n)).unwrap();
 
-    env_logger::init();
-
     Ok(())
 }