diff --git a/src/app.rs b/src/app.rs
index fd50dc0..b0ec5b0 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -2045,6 +2045,22 @@ impl App {
                 vec![]
             }
             KeyCode::Char('L') => {
+                if let Some(account) = self.account.as_deref() {
+                    if crate::screen::group_detail::is_admin(account, &self.group_admins) {
+                        let message = if self.group_admins.len() <= 1 {
+                            "You're the only admin. Promote another member to admin \
+                             before you can leave."
+                        } else {
+                            "You're an admin of this group. Step down as admin \
+                             before leaving."
+                        };
+                        self.popup = Some(Popup::Info {
+                            title: "Cannot Leave Group".into(),
+                            message: message.into(),
+                        });
+                        return vec![];
+                    }
+                }
                 let name = self
                     .group_detail
                     .as_ref()
@@ -3698,6 +3714,67 @@ mod tests {
         ));
     }
 
+    #[test]
+    fn admin_leave_is_blocked_and_explained() {
+        let mut app = app_on_group_detail();
+        app.account = Some("alicehex".into());
+        app.group_admins = vec![
+            json!({"pubkey": "alicehex", "display_name": "Alice"}),
+            json!({"pubkey": "bobhex", "display_name": "Bob"}),
+        ];
+        app.update(Action::Key(key(KeyCode::Char('L'))));
+        match app.popup {
+            Some(Popup::Info {
+                ref title,
+                ref message,
+            }) => {
+                assert_eq!(title, "Cannot Leave Group");
+                assert_eq!(
+                    message,
+                    "You're an admin of this group. Step down as admin before leaving."
+                );
+            }
+            other => panic!("expected Popup::Info, got {other:?}"),
+        }
+    }
+
+    #[test]
+    fn last_admin_leave_is_blocked_with_promotion_guidance() {
+        let mut app = app_on_group_detail();
+        app.account = Some("alicehex".into());
+        app.group_admins = vec![json!({"pubkey": "alicehex", "display_name": "Alice"})];
+        app.update(Action::Key(key(KeyCode::Char('L'))));
+        match app.popup {
+            Some(Popup::Info {
+                ref title,
+                ref message,
+            }) => {
+                assert_eq!(title, "Cannot Leave Group");
+                assert_eq!(
+                    message,
+                    "You're the only admin. Promote another member to admin \
+                     before you can leave."
+                );
+            }
+            other => panic!("expected Popup::Info, got {other:?}"),
+        }
+    }
+
+    #[test]
+    fn non_admin_leave_opens_confirm_popup() {
+        let mut app = app_on_group_detail();
+        app.account = Some("bobhex".into());
+        app.group_admins = vec![json!({"pubkey": "alicehex", "display_name": "Alice"})];
+        app.update(Action::Key(key(KeyCode::Char('L'))));
+        assert!(matches!(
+            app.popup,
+            Some(Popup::Confirm {
+                purpose: ConfirmPurpose::LeaveGroup,
+                ..
+            })
+        ));
+    }
+
     #[test]
     fn confirm_leave_emits_effect() {
         let mut app = app_on_group_detail();
diff --git a/src/screen/group_detail.rs b/src/screen/group_detail.rs
index d77cf54..8f3bd6a 100644
--- a/src/screen/group_detail.rs
+++ b/src/screen/group_detail.rs
@@ -19,12 +19,15 @@ fn field(val: &Value, keys: &[&str]) -> String {
     String::new()
 }
 
-/// Check if a member npub is in the admins list.
-fn is_admin(npub: &str, admins: &[Value]) -> bool {
+/// Check whether `pubkey` (hex, as returned by the daemon) appears in the admins list.
+///
+/// The admins list may contain bare strings or objects with `pubkey`/`npub` fields,
+/// so all three shapes are matched.
+pub fn is_admin(pubkey: &str, admins: &[Value]) -> bool {
     admins.iter().any(|a| {
-        a.as_str() == Some(npub)
-            || a.get("npub").and_then(|v| v.as_str()) == Some(npub)
-            || a.get("pubkey").and_then(|v| v.as_str()) == Some(npub)
+        a.as_str() == Some(pubkey)
+            || a.get("pubkey").and_then(|v| v.as_str()) == Some(pubkey)
+            || a.get("npub").and_then(|v| v.as_str()) == Some(pubkey)
     })
 }