diff --git a/aegisub/src/subs_edit_box.cpp b/aegisub/src/subs_edit_box.cpp
index 711befbea..dc0d73180 100644
--- a/aegisub/src/subs_edit_box.cpp
+++ b/aegisub/src/subs_edit_box.cpp
@@ -413,6 +413,7 @@ void SubsEditBox::PopulateActorList() {
 void SubsEditBox::OnActiveLineChanged(AssDialogue *new_line) {
 	wxEventBlocker blocker(this);
 	line = new_line;
+	commitId = -1;
 
 	Update(AssFile::COMMIT_DIAG_FULL);