diff --git a/xpcom/base/CycleCollectedJSRuntime.cpp b/xpcom/base/CycleCollectedJSRuntime.cpp
index 00d8f10b52b..ae936400627 100644
--- a/xpcom/base/CycleCollectedJSRuntime.cpp
+++ b/xpcom/base/CycleCollectedJSRuntime.cpp
@@ -1113,7 +1113,7 @@ IncrementalFinalizeRunnable::ReleaseNow(bool aLimited)
           break;
         }
       } else {
-        function.run(UINT32_MAX, function.data);
+        while (!function.run(UINT32_MAX, function.data));
         ++mFinalizeFunctionToRun;
       }
     } while (mFinalizeFunctionToRun < mDeferredFinalizeFunctions.Length());
diff --git a/xpcom/base/DeferredFinalize.h b/xpcom/base/DeferredFinalize.h
index 28e170d7f60..7d9c5888117 100644
--- a/xpcom/base/DeferredFinalize.h
+++ b/xpcom/base/DeferredFinalize.h
@@ -16,9 +16,10 @@ namespace mozilla {
 // the array.
 typedef void* (*DeferredFinalizeAppendFunction)(void* aPointers, void* aThing);
 
-// Called to finalize a number of objects. Slice is the number of objects
-// to finalize, or if it's UINT32_MAX, all objects should be finalized.
-// Return value indicates whether it finalized all objects in the buffer.
+// Called to finalize a number of objects. Slice is the number of objects to
+// finalize. The return value indicates whether it finalized all objects in the
+// buffer. If it returns true, the function will not be called again, so the
+// function should free aData.
 typedef bool (*DeferredFinalizeFunction)(uint32_t aSlice, void* aData);
 
 void DeferredFinalize(DeferredFinalizeAppendFunction aAppendFunc,