diff --git a/aegisub/src/ass_karaoke.cpp b/aegisub/src/ass_karaoke.cpp
index 47bfbcd0c..ff41971b5 100644
--- a/aegisub/src/ass_karaoke.cpp
+++ b/aegisub/src/ass_karaoke.cpp
@@ -48,7 +48,7 @@ AssKaraokeSyllable::AssKaraokeSyllable()
 	tag = 0;
 }
 
-void ParseAssKaraokeTags(AssDialogue *line, AssKaraokeVector &syls)
+void ParseAssKaraokeTags(const AssDialogue *line, AssKaraokeVector &syls)
 {
 	// Assume line already has tags parsed
 	AssKaraokeSyllable syl;
diff --git a/aegisub/src/ass_karaoke.h b/aegisub/src/ass_karaoke.h
index 9eef516dd..33bf4eb1d 100644
--- a/aegisub/src/ass_karaoke.h
+++ b/aegisub/src/ass_karaoke.h
@@ -50,4 +50,4 @@ struct AssKaraokeSyllable {
 
 typedef std::vector<AssKaraokeSyllable> AssKaraokeVector;
 
-void ParseAssKaraokeTags(AssDialogue *line, AssKaraokeVector &syls);
+void ParseAssKaraokeTags(const AssDialogue *line, AssKaraokeVector &syls);