diff -ur libmng-orig/libmng_zlib.c libmng-1.0.10/libmng_zlib.c
--- libmng_zlib.c	2005-12-15 00:53:13.000000000 +0100
+++ libmng_zlib.c	2007-07-19 13:17:44.000000000 +0200
@@ -162,6 +162,9 @@
 #ifdef MNG_SUPPORT_TRACE
   MNG_TRACE (pData, MNG_FN_ZLIB_INFLATEINIT, MNG_LC_START);
 #endif
+
+  if (pData->bInflating)               /* free the old zlib structures */
+     inflateEnd(&pData->sZlib);
                                        /* initialize zlib structures and such */
   iZrslt = inflateInit (&pData->sZlib);