diff --git a/crates/engine/src/lib.rs b/crates/engine/src/lib.rs
index 399bb1c88..c1de0c401 100644
--- a/crates/engine/src/lib.rs
+++ b/crates/engine/src/lib.rs
@@ -454,6 +454,10 @@ impl Session {
         if i < self.docs.len() {
             let d = self.docs.remove(i);
             self.groups.retain(|g| g.doc != d.uid);
+            // A macro being debugged in this workbook ends with it; its group just went.
+            if self.macro_debug.as_ref().is_some_and(|m| m.doc == d.uid) {
+                self.macro_debug = None;
+            }
             if self.active >= self.docs.len() {
                 self.active = self.docs.len().saturating_sub(1);
             }
diff --git a/crates/engine/src/tests/macros.rs b/crates/engine/src/tests/macros.rs
index 207e4c944..95e3b632e 100644
--- a/crates/engine/src/tests/macros.rs
+++ b/crates/engine/src/tests/macros.rs
@@ -232,6 +232,26 @@ fn shifting_makes_room_and_is_checked_again() {
     assert!(Arc::ptr_eq(&s.doc().unwrap().wb, &start));
 }
 
+#[test]
+fn closing_the_debugged_workbook_ends_the_debugger() {
+    // `file.close` is not an edit, so the debugger's lock lets it through; the group went with
+    // the document, and so must the debugger, or the next workbook could not debug anything and
+    // the state would report that no document is open.
+    let mut s = s();
+    data(&mut s);
+    put(&mut s, totals());
+    s.execute("macro.debug", json!({"action": "start", "name": "Totals", "inputs": "B2:C5", "breakpoints": ["1"]})).unwrap();
+    assert!(s.macro_debug.is_some());
+    s.execute("file.close", json!({"force": true})).unwrap();
+    assert!(s.macro_debug.is_none(), "the debugger ended with its workbook");
+    s.new_workbook();
+    data(&mut s);
+    put(&mut s, totals());
+    s.execute("macro.debug", json!({"action": "start", "name": "Totals", "inputs": "B2:C5", "breakpoints": ["1"]})).unwrap();
+    assert!(s.execute("macro.debug", json!({})).is_ok(), "the new workbook can be debugged");
+    s.execute("macro.debug", json!({"action": "stop"})).unwrap();
+}
+
 #[test]
 fn the_footprint_covers_other_sheets_objects_and_edges() {
     let mut s = s();