diff --git a/aegisub/src/initial_line_state.cpp b/aegisub/src/initial_line_state.cpp
index e8837b847..b7c0425b4 100644
--- a/aegisub/src/initial_line_state.cpp
+++ b/aegisub/src/initial_line_state.cpp
@@ -27,10 +27,15 @@ InitialLineState::InitialLineState(agi::Context *c)
 }
 
 void InitialLineState::OnActiveLineChanged(AssDialogue *new_line) {
-	if (new_line)
+	if (new_line) {
+		if (new_line->Id == line_id) return;
+		line_id = new_line->Id;
 		initial_text = new_line->Text;
-	else
+	}
+	else {
+		line_id = 0;
 		initial_text.clear();
+	}
 
 	InitialStateChanged(initial_text);
 }
diff --git a/aegisub/src/initial_line_state.h b/aegisub/src/initial_line_state.h
index 1bfa6ea3c..1230bab0a 100644
--- a/aegisub/src/initial_line_state.h
+++ b/aegisub/src/initial_line_state.h
@@ -24,6 +24,7 @@ class AssDialogue;
 class InitialLineState {
 	agi::signal::Connection active_line_connection;
 	wxString initial_text;
+	int line_id;
 
 	agi::signal::Signal<wxString const&> InitialStateChanged;
 	void OnActiveLineChanged(AssDialogue *new_line);