diff --git a/game/server/hl2/npc_combine.cpp b/game/server/hl2/npc_combine.cpp
index 09cae88a..afd1f8e2 100644
--- a/game/server/hl2/npc_combine.cpp
+++ b/game/server/hl2/npc_combine.cpp
@@ -2565,7 +2565,7 @@ void CNPC_Combine::SpeakSentence( int sentenceType )
 //=========================================================
 // PainSound
 //=========================================================
-void CNPC_Combine::PainSound ( void )
+void CNPC_Combine::PainSound ( const CTakeDamageInfo &damageinfo )
 {
 	// NOTE: The response system deals with this at the moment
 	if ( GetFlags() & FL_DISSOLVING )
diff --git a/game/server/hl2/npc_combine.h b/game/server/hl2/npc_combine.h
index ab166723c..3cbea2a7 100644
--- a/game/server/hl2/npc_combine.h
+++ b/game/server/hl2/npc_combine.h
@@ -126,7 +126,7 @@ public:
 	// Sounds
 	// -------------
 	void			DeathSound( void );
-	void			PainSound( void );
+	void			PainSound( const CTakeDamageInfo &damageinfo );
 	void			IdleSound( void );
 	void			AlertSound( void );
 	void			LostEnemySound( void );