diff --git a/dlls/windowscodecs/tgaformat.c b/dlls/windowscodecs/tgaformat.c
index f2a867aace0..2b8cb1a3cd6 100644
--- a/dlls/windowscodecs/tgaformat.c
+++ b/dlls/windowscodecs/tgaformat.c
@@ -292,7 +292,7 @@ static HRESULT WINAPI TgaDecoder_Initialize(IWICBitmapDecoder *iface, IStream *p
     This->image_offset = This->colormap_offset + This->colormap_length;
 
     /* Read footer if there is one */
-    seek.QuadPart = -sizeof(tga_footer);
+    seek.QuadPart = -(LONGLONG)sizeof(tga_footer);
     hr = IStream_Seek(pIStream, seek, STREAM_SEEK_END, NULL);
 
     if (SUCCEEDED(hr)) {