diff --git a/dlls/windowscodecs/tiffformat.c b/dlls/windowscodecs/tiffformat.c
index cd3703f70b4..d12729f55d9 100644
--- a/dlls/windowscodecs/tiffformat.c
+++ b/dlls/windowscodecs/tiffformat.c
@@ -643,6 +643,10 @@ static HRESULT WINAPI TiffDecoder_GetThumbnail(IWICBitmapDecoder *iface,
     IWICBitmapSource **ppIThumbnail)
 {
     TRACE("(%p,%p)\n", iface, ppIThumbnail);
+
+    if (!ppIThumbnail) return E_INVALIDARG;
+
+    *ppIThumbnail = NULL;
     return WINCODEC_ERR_CODECNOTHUMBNAIL;
 }