diff --git a/aegisub/src/subs_controller.cpp b/aegisub/src/subs_controller.cpp
index fd35d0070..c40cb70be 100644
--- a/aegisub/src/subs_controller.cpp
+++ b/aegisub/src/subs_controller.cpp
@@ -270,7 +270,9 @@ void SubsController::SetFileName(agi::fs::path const& path) {
 void SubsController::OnCommit(AssFileCommit c) {
 	if (c.message.empty() && !undo_stack.empty()) return;
 
-	++commit_id;
+	static int next_commit_id = 1;
+
+	commit_id = next_commit_id++;
 	// Allow coalescing only if it's the last change and the file has not been
 	// saved since the last change
 	if (commit_id == *c.commit_id+1 && redo_stack.empty() && saved_commit_id+1 != commit_id && autosaved_commit_id+1 != commit_id) {