diff --git a/aegisub/src/ass_file.h b/aegisub/src/ass_file.h
index ada5ce446..5b780b8fe 100644
--- a/aegisub/src/ass_file.h
+++ b/aegisub/src/ass_file.h
@@ -152,7 +152,7 @@ public:
 	/// Get the value in a [Script Info] key as string.
 	wxString GetScriptInfo(const wxString key);
 	/// Set the value of a [Script Info] key. Adds it if it doesn't exist.
-	void SetScriptInfo(wxString key, wxString const& value);
+	void SetScriptInfo(wxString const& key, wxString const& value);
 	// Add a ";" comment in the [Script Info] section
 	void AddComment(const wxString comment);
 	/// @brief Add a line to the file