diff --git a/proto/anki/frontend.proto b/proto/anki/frontend.proto
index 95b929c5c..1d733a369 100644
--- a/proto/anki/frontend.proto
+++ b/proto/anki/frontend.proto
@@ -27,6 +27,9 @@ service FrontendService {
   rpc deckOptionsRequireClose(generic.Empty) returns (generic.Empty);
   // Warns python that the deck option web view is ready to receive requests.
   rpc deckOptionsReady(generic.Empty) returns (generic.Empty);
+
+  // Save colour picker's custom colour palette
+  rpc SaveCustomColours(generic.Empty) returns (generic.Empty);
 }
 
 service BackendFrontendService {}
diff --git a/qt/aqt/mediasrv.py b/qt/aqt/mediasrv.py
index 820e762d9..7c3480237 100644
--- a/qt/aqt/mediasrv.py
+++ b/qt/aqt/mediasrv.py
@@ -599,6 +599,18 @@ def deck_options_ready() -> bytes:
     return b""
 
 
+def save_custom_colours() -> bytes:
+    colours = ",".join(
+        [
+            QColorDialog.customColor(i).name(QColor.NameFormat.HexArgb)
+            for i in range(QColorDialog.customCount())
+        ]
+    )
+    assert aqt.mw.pm.profile is not None
+    aqt.mw.pm.profile["customColorPickerPalette"] = colours
+    return b""
+
+
 post_handler_list = [
     congrats_info,
     get_deck_configs_for_update,
@@ -614,6 +626,7 @@ post_handler_list = [
     search_in_browser,
     deck_options_require_close,
     deck_options_ready,
+    save_custom_colours,
 ]