MinGW does not support EOPNOTSUPP.

By purpose, whatever that purpose is. See:
http://sourceforge.net/p/mingw/bugs/263/

lib/zip_open.c

diff --git a/lib/zip_open.c b/lib/zip_open.c
index fb9c566..f683bd2 100644
--- a/lib/zip_open.c
+++ b/lib/zip_open.c
@@ -39,6 +39,13 @@
 #include <stdlib.h>
 #include <string.h>
 
+/* at least MinGW does not provide this error code, see
+ * http://sourceforge.net/p/mingw/bugs/263/
+ */
+#ifndef EOPNOTSUPP
+#define EOPNOTSUPP EINVAL
+#endif
+
 #include "zipint.h"
 
 typedef enum {