diff --git a/aegisub/src/ass_dialogue.h b/aegisub/src/ass_dialogue.h
index 8213a24f4..0476454a9 100644
--- a/aegisub/src/ass_dialogue.h
+++ b/aegisub/src/ass_dialogue.h
@@ -215,7 +215,7 @@ public:
 	void UpdateText();
 	const wxString GetEntryData() const;
 	/// Do nothing
-	void SetEntryData(wxString) { }
+	void SetEntryData(wxString const&) { }
 
 	template<int which>
 	void SetMarginString(const wxString value) { SetMarginString(value, which);}