diff --git a/dlls/dmsynth/dmsynth_main.c b/dlls/dmsynth/dmsynth_main.c
index 014eb0eb6f1..a5e2e605419 100644
--- a/dlls/dmsynth/dmsynth_main.c
+++ b/dlls/dmsynth/dmsynth_main.c
@@ -29,7 +29,7 @@ LONG DMSYNTH_refCount = 0;
 
 typedef struct {
         IClassFactory IClassFactory_iface;
-        HRESULT WINAPI (*fnCreateInstance)(REFIID riid, void **ppv);
+        HRESULT (*fnCreateInstance)(REFIID riid, void **ppv);
 } IClassFactoryImpl;
 
 /******************************************************************
diff --git a/dlls/dmsynth/dmsynth_private.h b/dlls/dmsynth/dmsynth_private.h
index 0058ce04d3a..b0e4c66f416 100644
--- a/dlls/dmsynth/dmsynth_private.h
+++ b/dlls/dmsynth/dmsynth_private.h
@@ -49,8 +49,8 @@ typedef struct IDirectMusicSynthSinkImpl IDirectMusicSynthSinkImpl;
 /*****************************************************************************
  * ClassFactory
  */
-extern HRESULT WINAPI DMUSIC_CreateDirectMusicSynthImpl(REFIID riid, void **ppobj) DECLSPEC_HIDDEN;
-extern HRESULT WINAPI DMUSIC_CreateDirectMusicSynthSinkImpl(REFIID riid, void **ppobj) DECLSPEC_HIDDEN;
+extern HRESULT DMUSIC_CreateDirectMusicSynthImpl(REFIID riid, void **ppobj) DECLSPEC_HIDDEN;
+extern HRESULT DMUSIC_CreateDirectMusicSynthSinkImpl(REFIID riid, void **ppobj) DECLSPEC_HIDDEN;
 
 /*****************************************************************************
  * IDirectMusicSynth8Impl implementation structure
diff --git a/dlls/dmsynth/synth.c b/dlls/dmsynth/synth.c
index d96ee943a5e..121d9aadf35 100644
--- a/dlls/dmsynth/synth.c
+++ b/dlls/dmsynth/synth.c
@@ -729,7 +729,7 @@ static const IKsControlVtbl DMSynthImpl_IKsControl_Vtbl = {
 };
 
 /* for ClassFactory */
-HRESULT WINAPI DMUSIC_CreateDirectMusicSynthImpl(REFIID riid, void **ppobj)
+HRESULT DMUSIC_CreateDirectMusicSynthImpl(REFIID riid, void **ppobj)
 {
     IDirectMusicSynth8Impl *obj;
     HRESULT hr;
diff --git a/dlls/dmsynth/synthsink.c b/dlls/dmsynth/synthsink.c
index d34bcf9df5e..a277a05bafb 100644
--- a/dlls/dmsynth/synthsink.c
+++ b/dlls/dmsynth/synthsink.c
@@ -298,7 +298,7 @@ static const IKsControlVtbl DMSynthSinkImpl_IKsControl_Vtbl = {
 };
 
 /* for ClassFactory */
-HRESULT WINAPI DMUSIC_CreateDirectMusicSynthSinkImpl(REFIID riid, void **ret_iface)
+HRESULT DMUSIC_CreateDirectMusicSynthSinkImpl(REFIID riid, void **ret_iface)
 {
     IDirectMusicSynthSinkImpl *obj;
     HRESULT hr;