Index: zlib.h
===================================================================
--- zlib.h.orig
+++ zlib.h
@@ -1256,7 +1256,11 @@ ZEXTERN int ZEXPORT gzwrite OF((gzFile f
    error.
 */
 
-ZEXTERN int ZEXPORTVA gzprintf OF((gzFile file, const char *format, ...));
+ZEXTERN int ZEXPORTVA gzprintf OF((gzFile file, const char *format, ...))
+#ifdef __GNUC__
+       __attribute__((__format__(__printf__,2,3)))
+#endif
+;
 /*
      Converts, formats, and writes the arguments to the compressed file under
    control of the format string, as in fprintf.  gzprintf returns the number of