diff --git a/dlls/quartz/filesource.c b/dlls/quartz/filesource.c
index 71724af700c..9e3605757b6 100644
--- a/dlls/quartz/filesource.c
+++ b/dlls/quartz/filesource.c
@@ -1292,6 +1292,8 @@ static BOOL sync_read(HANDLE file, LONGLONG offset, LONG length, BYTE *buffer, D
     ovl.u.s.Offset = (DWORD)offset;
     ovl.u.s.OffsetHigh = offset >> 32;
 
+    *read_len = 0;
+
     ret = ReadFile(file, buffer, length, NULL, &ovl);
     if (ret || GetLastError() == ERROR_IO_PENDING)
         ret = GetOverlappedResult(file, &ovl, read_len, TRUE);
@@ -1331,6 +1333,9 @@ static HRESULT WINAPI FileAsyncReader_SyncReadAligned(IAsyncReader *iface, IMedi
             hr = HRESULT_FROM_WIN32(GetLastError());
     }
 
+    if (SUCCEEDED(hr))
+        IMediaSample_SetActualDataLength(sample, read_len);
+
     return hr;
 }
 
diff --git a/dlls/quartz/tests/filesource.c b/dlls/quartz/tests/filesource.c
index 340d1c4e2ec..36a25395cd5 100644
--- a/dlls/quartz/tests/filesource.c
+++ b/dlls/quartz/tests/filesource.c
@@ -687,7 +687,6 @@ static void test_sync_read_aligned(IAsyncReader *reader, IMemAllocator *allocato
     ok(hr == S_OK, "Got hr %#x.\n", hr);
 
     len = IMediaSample_GetActualDataLength(sample);
-todo_wine
     ok(len == 512, "Got length %d.\n", len);
 
     for (i = 0; i < 512; i++)
@@ -702,7 +701,6 @@ todo_wine
     ok(hr == S_FALSE, "Got hr %#x.\n", hr);
 
     len = IMediaSample_GetActualDataLength(sample);
-todo_wine
     ok(len == 88, "Got length %d.\n", len);
 
     for (i = 0; i < 88; i++)
@@ -717,7 +715,6 @@ todo_wine
     ok(hr == S_OK, "Got hr %#x.\n", hr);
 
     len = IMediaSample_GetActualDataLength(sample);
-todo_wine
     ok(len == 0, "Got length %d.\n", len);
 
     IMediaSample_Release(sample);