Index: zlib-1.2.5_git201105121450/gzlib.c
===================================================================
--- zlib-1.2.5_git201105121450.orig/gzlib.c	2011-05-12 16:50:18.000000000 +0200
+++ zlib-1.2.5_git201105121450/gzlib.c	2011-05-27 10:45:36.467678080 +0200
@@ -91,6 +91,9 @@
 {
     gz_statep state;
 
+    if (!path || !mode)
+        return NULL;
+
     /* allocate gzFile structure to return */
     state = malloc(sizeof(gz_state));
     if (state == NULL)