--- a/zconf.h.in
+++ b/zconf.h.in
@@ -380,7 +380,11 @@
 #endif
 
 #ifndef ZEXTERN
-#  define ZEXTERN extern
+#  ifdef HAVE_HIDDEN
+#    define ZEXTERN extern __attribute__((visibility ("default")))
+#  else
+#    define ZEXTERN extern
+#  endif
 #endif
 #ifndef ZEXPORT
 #  define ZEXPORT