diff --git a/src/gamedata/d_dehacked.cpp b/src/gamedata/d_dehacked.cpp
index f12a0fcdf..fa744e63b 100644
--- a/src/gamedata/d_dehacked.cpp
+++ b/src/gamedata/d_dehacked.cpp
@@ -184,7 +184,7 @@ struct MBFParamState
 	int GetSoundArg(int i, int def = 0)
 	{
 		int num = argsused & (1 << i) ? (int)args[i] : def;
-		if (num > 0 && num < int(SoundMap.Size())) return SoundMap[num];
+		if (num > 0 && num <= int(SoundMap.Size())) return SoundMap[num-1];
 		return 0;
 	}