diff --git a/aegisub/src/ffmpegsource_common.cpp b/aegisub/src/ffmpegsource_common.cpp
index cd811bd95..dcc9e2dad 100644
--- a/aegisub/src/ffmpegsource_common.cpp
+++ b/aegisub/src/ffmpegsource_common.cpp
@@ -103,13 +103,19 @@ FFMS_Index *FFmpegSourceProvider::DoIndexing(FFMS_Indexer *Indexer, agi::fs::pat
 	// index all audio tracks
 	FFMS_Index *Index;
 	Progress.Run([&](agi::ProgressSink *ps) {
+		struct progress {
+			agi::ProgressSink *ps;
+			int calls;
+		};
+		progress state = { ps, 0 };
 		Index = FFMS_DoIndexing(Indexer, Trackmask, FFMS_TRACKMASK_NONE, nullptr, nullptr, IndexEH,
 			static_cast<TIndexCallback>([](int64_t Current, int64_t Total, void *Private) -> int {
-				agi::ProgressSink *ps = static_cast<agi::ProgressSink*>(Private);
-				ps->SetProgress(Current, Total);
-				return ps->IsCancelled();
+				auto state = static_cast<progress *>(Private);
+				if (++state->calls % 10 == 0)
+					state->ps->SetProgress(Current, Total);
+				return state->ps->IsCancelled();
 			}),
-			ps, &ErrInfo);
+			&state, &ErrInfo);
 	});
 
 	if (Index == nullptr) {