diff --git a/crates/nu-protocol/src/signature.rs b/crates/nu-protocol/src/signature.rs
index 7efe43583f..12557c85a1 100644
--- a/crates/nu-protocol/src/signature.rs
+++ b/crates/nu-protocol/src/signature.rs
@@ -274,7 +274,10 @@ impl Signature {
         short: Option<char>,
     ) -> Signature {
         let s = short.and_then(|c| {
-            debug_assert!(!self.get_shorts().contains(&c));
+            debug_assert!(
+                !self.get_shorts().contains(&c),
+                "There may be duplicate short flags, such as -h"
+            );
             Some(c)
         });