diff --git a/sp/src/game/server/baseentity.h b/sp/src/game/server/baseentity.h
index 1f2f75e15b1..1453d859433 100644
--- a/sp/src/game/server/baseentity.h
+++ b/sp/src/game/server/baseentity.h
@@ -1575,7 +1575,7 @@ class CBaseEntity : public IServerEntity
 		float flVolume, soundlevel_t iSoundlevel, int iFlags = 0, int iPitch = PITCH_NORM,
 		const Vector *pOrigin = NULL, const Vector *pDirection = NULL, bool bUpdatePositions = true, float soundtime = 0.0f
 #ifdef MAPBASE
-		, int iSpecialDSP = 0, int iSpeakerIndex = 0 // Needed for env_microphone
+		, int iSpecialDSP = 0, int iSpeakerIndex = -1 // Needed for env_microphone
 #endif
 		);