diff -ru optipng-0.4.8.orig/lib/zlib/inftrees.c optipng-0.4.8/lib/zlib/inftrees.c
--- optipng-0.4.8.orig/lib/zlib/inftrees.c	2004-09-15 15:30:06.000000000 +0100
+++ optipng-0.4.8/lib/zlib/inftrees.c	2005-10-07 17:13:03.069420200 +0100
@@ -134,7 +134,7 @@
         left -= count[len];
         if (left < 0) return -1;        /* over-subscribed */
     }
-    if (left > 0 && (type == CODES || (codes - count[0] != 1)))
+    if (left > 0 && (type == CODES || max != 1))
         return -1;                      /* incomplete set */
 
     /* generate offsets into symbol table for each length for sorting */
diff -ru optipng-0.4.8.orig/lib/zlib/inftrees.h optipng-0.4.8/lib/zlib/inftrees.h
--- optipng-0.4.8.orig/lib/zlib/inftrees.h	2003-08-10 23:15:50.000000000 +0100
+++ optipng-0.4.8/lib/zlib/inftrees.h	2005-10-07 17:13:49.953292768 +0100
@@ -36,12 +36,12 @@
  */
 
 /* Maximum size of dynamic tree.  The maximum found in a long but non-
-   exhaustive search was 1004 code structures (850 for length/literals
-   and 154 for distances, the latter actually the result of an
+   exhaustive search was 1444 code structures (852 for length/literals
+   and 592 for distances, the latter actually the result of an
    exhaustive search).  The true maximum is not known, but the value
    below is more than safe. */
-#define ENOUGH 1440
-#define MAXD 154
+#define ENOUGH 2048
+#define MAXD 592
 
 /* Type of code to build for inftable() */
 typedef enum {