diff --git a/utils_unix.go b/utils_unix.go
index fc49492..b1924ea 100644
--- a/utils_unix.go
+++ b/utils_unix.go
@@ -1,4 +1,4 @@
-// +build aix darwin dragonfly freebsd linux,!appengine netbsd openbsd os400 solaris
+// +build aix darwin dragonfly freebsd linux,!appengine netbsd openbsd os400 solaris zos
 
 package readline