diff --git a/dlls/winmm/mmio.c b/dlls/winmm/mmio.c
index 60b6d0fd4a6..a750bf263e6 100644
--- a/dlls/winmm/mmio.c
+++ b/dlls/winmm/mmio.c
@@ -667,10 +667,11 @@ HMMIO MMIO_Open(LPSTR szFileName, MMIOINFO* refmminfo, DWORD dwOpenFlags,
         refmminfo->wErrorRet = MMIO_SetBuffer(wm, refmminfo->pchBuffer, refmminfo->cchBuffer, 0);
 	if (refmminfo->wErrorRet != MMSYSERR_NOERROR)
 	    goto error1;
-	if (wm->info.fccIOProc == FOURCC_MEM)
-	    wm->bBufferLoaded = TRUE;
     }
 
+    if (wm->info.fccIOProc == FOURCC_MEM && !(wm->info.dwFlags & MMIO_ALLOCBUF))
+        wm->bBufferLoaded = TRUE;
+
     /* see mmioDosIOProc for that one */
     wm->info.adwInfo[0] = refmminfo->adwInfo[0];