diff --git a/Lib/zipfile.py b/Lib/zipfile.py
index ff7f30f..fa6a433 100644
--- a/Lib/zipfile.py
+++ b/Lib/zipfile.py
@@ -1053,6 +1053,10 @@
         if fheader[_FH_EXTRA_FIELD_LENGTH]:
             zef_file.read(fheader[_FH_EXTRA_FIELD_LENGTH])
 
+        if zinfo.flag_bits & 0x20:
+            # Zip 2.7: compressed patched data
+            raise NotImplementedError("compressed patched data (flag bit 5)")
+
         if zinfo.flag_bits & 0x800:
             # UTF-8 filename
             fname_str = fname.decode("utf-8")