diff --git a/clap_builder/src/output/usage.rs b/clap_builder/src/output/usage.rs
index dd99c63c7b7..87bb945283d 100644
--- a/clap_builder/src/output/usage.rs
+++ b/clap_builder/src/output/usage.rs
@@ -439,7 +439,7 @@ impl<'cmd> Usage<'cmd> {
                 required_groups.insert(elem);
                 required_groups_members.extend(group_members);
             } else {
-                debug_assert!(self.cmd.find(req).is_some());
+                debug_assert!(self.cmd.find(req).is_some(), "`{req}` must exist");
             }
         }