--- zlib.h.orig
+++ zlib.h
@@ -696,7 +696,7 @@ ZEXTERN uLong ZEXPORT deflateBound OF((z
    be larger than the value returned by deflateBound() if flush options other
    than Z_FINISH or Z_NO_FLUSH are used.
 */
-    
+
 ZEXTERN int ZEXPORT deflatePending OF((z_streamp strm,
                                        unsigned *pending,
                                        int *bits));
@@ -706,7 +706,7 @@ ZEXTERN int ZEXPORT deflatePending OF((z
    provided would be due to the available output space having being consumed.
    The number of bits of output not provided are between 0 and 7, where they
    await more bits to join them in order to fill out a full byte.
- 
+
      deflatePending returns Z_OK if success, or Z_STREAM_ERROR if the source
    stream state was inconsistent.
  */
@@ -1280,7 +1280,10 @@ ZEXTERN int ZEXPORT gzwrite OF((gzFile f
    error.
 */
 
-ZEXTERN int ZEXPORTVA gzprintf ON((gzFile file, const char *format, ...));
+ZEXTERN 
+__attribute__((__format__(__printf__,2,3))) 
+int ZEXPORTVA gzprintf ON((gzFile file, const char *format, ...));
+
 /*
      Converts, formats, and writes the arguments to the compressed file under
    control of the format string, as in fprintf.  gzprintf returns the number of