diff --git a/src/audio/AudioManager.h b/src/audio/AudioManager.h
index 7c591a1e..b836f221 100644
--- a/src/audio/AudioManager.h
+++ b/src/audio/AudioManager.h
@@ -485,7 +485,7 @@ public:
 	void InitialisePoliceRadioZones();
 	void InitialisePoliceRadio();
 	void ResetPoliceRadio();
-	void SetMissionScriptPoliceAudio(int32 sfx);
+	void SetMissionScriptPoliceAudio(uint32 sfx);
 	int8 GetMissionScriptPoliceAudioPlayingStatus();
 	void DoPoliceRadioCrackle();
 	void ServicePoliceRadio();
diff --git a/src/audio/PolRadio.cpp b/src/audio/PolRadio.cpp
index 9a98de35..6fc1ceef 100644
--- a/src/audio/PolRadio.cpp
+++ b/src/audio/PolRadio.cpp
@@ -106,7 +106,7 @@ cAudioManager::ResetPoliceRadio()
 }
 
 void
-cAudioManager::SetMissionScriptPoliceAudio(int32 sfx)
+cAudioManager::SetMissionScriptPoliceAudio(uint32 sfx)
 {
 	if (!m_bIsInitialised) return;
 	if (g_nMissionAudioPlayingStatus != 1) {