diff --git a/proto/anki/card_rendering.proto b/proto/anki/card_rendering.proto
index 2c544dd9b..7be401a1a 100644
--- a/proto/anki/card_rendering.proto
+++ b/proto/anki/card_rendering.proto
@@ -29,14 +29,14 @@ service CardRenderingService {
   rpc CompareAnswer(CompareAnswerRequest) returns (generic.String);
   rpc ExtractClozeForTyping(ExtractClozeForTypingRequest)
       returns (generic.String);
-  rpc AllTtsVoices(AllTtsVoicesRequest) returns (AllTtsVoicesResponse);
-  rpc WriteTtsStream(WriteTtsStreamRequest) returns (generic.Empty);
 }
 
 // Implicitly includes any of the above methods that are not listed in the
 // backend service.
 service BackendCardRenderingService {
   rpc StripHtml(StripHtmlRequest) returns (generic.String);
+  rpc AllTtsVoices(AllTtsVoicesRequest) returns (AllTtsVoicesResponse);
+  rpc WriteTtsStream(WriteTtsStreamRequest) returns (generic.Empty);
 }
 
 message ExtractAvTagsRequest {
diff --git a/rslib/src/backend/card_rendering.rs b/rslib/src/backend/card_rendering.rs
index 7c4520948..e202c0284 100644
--- a/rslib/src/backend/card_rendering.rs
+++ b/rslib/src/backend/card_rendering.rs
@@ -4,6 +4,8 @@ use anki_proto::card_rendering::StripHtmlRequest;
 
 use crate::backend::Backend;
 use crate::card_rendering::service::strip_html_proto;
+use crate::card_rendering::tts;
+use crate::prelude::*;
 use crate::services::BackendCardRenderingService;
 
 impl BackendCardRenderingService for Backend {
@@ -13,4 +15,25 @@ impl BackendCardRenderingService for Backend {
     ) -> crate::error::Result<anki_proto::generic::String> {
         strip_html_proto(input)
     }
+
+    fn all_tts_voices(
+        &self,
+        input: anki_proto::card_rendering::AllTtsVoicesRequest,
+    ) -> Result<anki_proto::card_rendering::AllTtsVoicesResponse> {
+        tts::all_voices(input.validate)
+            .map(|voices| anki_proto::card_rendering::AllTtsVoicesResponse { voices })
+    }
+
+    fn write_tts_stream(
+        &self,
+        request: anki_proto::card_rendering::WriteTtsStreamRequest,
+    ) -> Result<()> {
+        tts::write_stream(
+            &request.path,
+            &request.voice_id,
+            request.speed,
+            &request.text,
+        )
+        .map(Into::into)
+    }
 }
diff --git a/rslib/src/card_rendering/service.rs b/rslib/src/card_rendering/service.rs
index c9cd203f0..4ee15f26c 100644
--- a/rslib/src/card_rendering/service.rs
+++ b/rslib/src/card_rendering/service.rs
@@ -7,7 +7,6 @@ use anki_proto::generic;
 use crate::card::CardId;
 use crate::card_rendering::extract_av_tags;
 use crate::card_rendering::strip_av_tags;
-use crate::card_rendering::tts;
 use crate::cloze::extract_cloze_for_typing;
 use crate::collection::Collection;
 use crate::error::OrInvalid;
@@ -167,27 +166,6 @@ impl crate::services::CardRenderingService for Collection {
             .to_string()
             .into())
     }
-
-    fn all_tts_voices(
-        &mut self,
-        input: anki_proto::card_rendering::AllTtsVoicesRequest,
-    ) -> Result<anki_proto::card_rendering::AllTtsVoicesResponse> {
-        tts::all_voices(input.validate)
-            .map(|voices| anki_proto::card_rendering::AllTtsVoicesResponse { voices })
-    }
-
-    fn write_tts_stream(
-        &mut self,
-        request: anki_proto::card_rendering::WriteTtsStreamRequest,
-    ) -> Result<()> {
-        tts::write_stream(
-            &request.path,
-            &request.voice_id,
-            request.speed,
-            &request.text,
-        )
-        .map(Into::into)
-    }
 }
 
 fn rendered_nodes_to_proto(