diff --git a/dlls/dsound/dsound_private.h b/dlls/dsound/dsound_private.h
index 2d87263f8d2..c16f1c1535c 100644
--- a/dlls/dsound/dsound_private.h
+++ b/dlls/dsound/dsound_private.h
@@ -456,7 +456,7 @@ void DSOUND_MixToTemporary(const IDirectSoundBufferImpl *dsb, DWORD writepos, DW
 DWORD DSOUND_secpos_to_bufpos(const IDirectSoundBufferImpl *dsb, DWORD secpos, DWORD secmixpos, DWORD* overshot);
 
 void CALLBACK DSOUND_timer(UINT timerID, UINT msg, DWORD_PTR dwUser, DWORD_PTR dw1, DWORD_PTR dw2);
-void CALLBACK DSOUND_callback(HWAVEOUT hwo, UINT msg, DWORD dwUser, DWORD dw1, DWORD dw2);
+void CALLBACK DSOUND_callback(HWAVEOUT hwo, UINT msg, DWORD_PTR dwUser, DWORD_PTR dw1, DWORD_PTR dw2);
 
 /* sound3d.c */
 
diff --git a/dlls/dsound/mixer.c b/dlls/dsound/mixer.c
index efcb21b32b4..3bcbce02f7d 100644
--- a/dlls/dsound/mixer.c
+++ b/dlls/dsound/mixer.c
@@ -1026,10 +1026,10 @@ void CALLBACK DSOUND_timer(UINT timerID, UINT msg, DWORD_PTR dwUser,
 	TRACE("completed processing at %d, duration = %d\n", end_time, end_time - start_time);
 }
 
-void CALLBACK DSOUND_callback(HWAVEOUT hwo, UINT msg, DWORD dwUser, DWORD dw1, DWORD dw2)
+void CALLBACK DSOUND_callback(HWAVEOUT hwo, UINT msg, DWORD_PTR dwUser, DWORD_PTR dw1, DWORD_PTR dw2)
 {
 	DirectSoundDevice * device = (DirectSoundDevice*)dwUser;
-	TRACE("(%p,%x,%x,%x,%x)\n",hwo,msg,dwUser,dw1,dw2);
+	TRACE("(%p,%x,%lx,%lx,%lx)\n",hwo,msg,dwUser,dw1,dw2);
 	TRACE("entering at %d, msg=%08x(%s)\n", GetTickCount(), msg,
 		msg==MM_WOM_DONE ? "MM_WOM_DONE" : msg==MM_WOM_CLOSE ? "MM_WOM_CLOSE" : 
 		msg==MM_WOM_OPEN ? "MM_WOM_OPEN" : "UNKNOWN");