diff --git a/dlls/quartz/memallocator.c b/dlls/quartz/memallocator.c
index 3cabe12f991..f9c64ac9bb3 100644
--- a/dlls/quartz/memallocator.c
+++ b/dlls/quartz/memallocator.c
@@ -683,7 +683,10 @@ static HRESULT WINAPI StdMediaSample2_SetDiscontinuity(IMediaSample2 * iface, BO
 
     TRACE("(%s)\n", bIsDiscontinuity ? "TRUE" : "FALSE");
 
-    This->props.dwSampleFlags = (This->props.dwSampleFlags & ~AM_SAMPLE_DATADISCONTINUITY) | bIsDiscontinuity ? AM_SAMPLE_DATADISCONTINUITY : 0;
+    if (bIsDiscontinuity)
+        This->props.dwSampleFlags |= AM_SAMPLE_DATADISCONTINUITY;
+    else
+        This->props.dwSampleFlags &= ~AM_SAMPLE_DATADISCONTINUITY;
 
     return S_OK;
 }