diff --git a/engines/sci/engine/kernel.cpp b/engines/sci/engine/kernel.cpp
index ec96c6c3e9b..14e6e2de71b 100644
--- a/engines/sci/engine/kernel.cpp
+++ b/engines/sci/engine/kernel.cpp
@@ -360,7 +360,7 @@ static const SciKernelMapSubEntry kDoSound_subops[] = {
     { SIG_SOUNDSCI1EARLY, 10, MAP_CALL(DoSoundFade),               "oiiii",                NULL },
     { SIG_SOUNDSCI1EARLY, 11, MAP_CALL(DoSoundUpdateCues),         "o",                    NULL },
     { SIG_SOUNDSCI1EARLY, 12, MAP_CALL(DoSoundSendMidi),           "oiii",                 NULL },
-    { SIG_SOUNDSCI1EARLY, 13, MAP_CALL(DoSoundReverb),             "oi",                   NULL },
+    { SIG_SOUNDSCI1EARLY, 13, MAP_CALL(DoSoundReverb),             "i",                    NULL },
     { SIG_SOUNDSCI1EARLY, 14, MAP_CALL(DoSoundSetHold),            "oi",                   NULL },
     { SIG_SOUNDSCI1EARLY, 15, MAP_CALL(DoSoundDummy),              "",                     NULL },
     //  ^^ Longbow demo