diff --git a/src/shells/zsh.rs b/src/shells/zsh.rs
index bdc5569a..736cdd07 100644
--- a/src/shells/zsh.rs
+++ b/src/shells/zsh.rs
@@ -463,7 +463,8 @@ fn write_positionals_of(p: &App) -> String {
                 .help
                 .map_or("".to_owned(), |v| " -- ".to_owned() + v)
                 .replace("[", "\\[")
-                .replace("]", "\\]"),
+                .replace("]", "\\]")
+                .replace(":", "\\:"),
             action = arg
                 .possible_vals
                 .as_ref()