diff --git a/dlls/quartz/memallocator.c b/dlls/quartz/memallocator.c
index 91c23736fd0..5ac8a72a818 100644
--- a/dlls/quartz/memallocator.c
+++ b/dlls/quartz/memallocator.c
@@ -685,8 +685,15 @@ static HRESULT WINAPI StdMediaSample2_SetMediaType(IMediaSample2 * iface, AM_MED
         DeleteMediaType(This->props.pMediaType);
         This->props.pMediaType = NULL;
     }
+
     if (!pMediaType)
+    {
+        This->props.dwSampleFlags &= ~AM_SAMPLE_TYPECHANGED;
         return S_OK;
+    }
+
+    This->props.dwSampleFlags |= AM_SAMPLE_TYPECHANGED;
+
     if (!(This->props.pMediaType = CoTaskMemAlloc(sizeof(AM_MEDIA_TYPE))))
         return E_OUTOFMEMORY;
 
diff --git a/dlls/quartz/tests/memallocator.c b/dlls/quartz/tests/memallocator.c
index 9bbfd425cfa..164f3af47f4 100644
--- a/dlls/quartz/tests/memallocator.c
+++ b/dlls/quartz/tests/memallocator.c
@@ -509,7 +509,7 @@ static void test_sample_properties(void)
 
     hr = IMediaSample2_GetProperties(sample2, sizeof(props), (BYTE *)&props);
     ok(hr == S_OK, "Got hr %#x.\n", hr);
-    todo_wine ok(props.dwSampleFlags == AM_SAMPLE_TYPECHANGED, "Got flags %#x.\n", props.dwSampleFlags);
+    ok(props.dwSampleFlags == AM_SAMPLE_TYPECHANGED, "Got flags %#x.\n", props.dwSampleFlags);
     ok(!memcmp(props.pMediaType, &expect_mt, sizeof(AM_MEDIA_TYPE)), "Media types didn't match.\n");
 
     hr = IMediaSample_SetMediaType(sample, NULL);