diff -ur pngcheck-2.3.0_o/pngcheck.c pngcheck-2.3.0/pngcheck.c
--- pngcheck-2.3.0_o/pngcheck.c	2007-07-08 07:23:31.000000000 +0100
+++ pngcheck-2.3.0/pngcheck.c	2018-04-11 15:05:17.144145056 +0100
@@ -672,9 +672,6 @@
       check_zlib = 0;
       if (verbose > 1)
         verbose = 1;
-    } else if (strcmp(zlib_version, ZLIB_VERSION) != 0) {
-      printf("zlib warning:  different version (expected %s,"
-        " using %s)\n\n", ZLIB_VERSION, zlib_version);
     }
 #endif /* USE_ZLIB */