diff --git a/shell/source/win32/zipfile/zipfile.cxx b/shell/source/win32/zipfile/zipfile.cxx
index ceccb7a3b2a7..ca4381241231 100644
--- a/shell/source/win32/zipfile/zipfile.cxx
+++ b/shell/source/win32/zipfile/zipfile.cxx
@@ -289,7 +289,7 @@ static bool findCentralDirectoryEnd(StreamInterface *stream)
 
     try
     {
-        for (long nOffset = nLength - BLOCK_SIZE;
+        for (long nOffset = nLength - BLOCK_SIZE - 4;
              nOffset > 0; nOffset -= BLOCK_SIZE)
         {
             if (findSignatureAtOffset(stream, nOffset))