diff --git a/source/core/music/s_advsound.cpp b/source/core/music/s_advsound.cpp
index bbe0bf70d..7e4ffb4b6 100644
--- a/source/core/music/s_advsound.cpp
+++ b/source/core/music/s_advsound.cpp
@@ -425,6 +425,10 @@ static void S_AddSNDINFO (int lump)
 
 			default:
 			{ // Got a logical sound mapping
+				if (sc.String[0] == '$')
+				{
+					sc.ScriptError("%s: Unknown keyword");
+				}
 				FString name (sc.String);
 				if (wantassigns == -1)
 				{