diff --git a/crates/engine/src/cmd/browser.rs b/crates/engine/src/cmd/browser.rs
index acb1f4a9..710f76e7 100644
--- a/crates/engine/src/cmd/browser.rs
+++ b/crates/engine/src/cmd/browser.rs
@@ -445,13 +445,14 @@ fn rename_body(s: &mut Session, p: &Value) -> Result<Value> {
     if st.body(name).is_some() {
         return Err(bad(cmd, format!("another body is called `{name}`")));
     }
-    // The body is the k-th new body of its feature; the names before it are kept as they are.
+    // The body is the k-th new body of its feature; its siblings keep the names they have now
+    // (unpinned pattern copies would otherwise be renumbered into the freed name, #265).
     let fid = b.feature;
     let siblings: Vec<String> = st.bodies.iter().filter(|x| x.feature == fid).map(|x| x.name.clone()).collect();
     let k = siblings.iter().position(|n| *n == old).unwrap_or(0);
     let d = s.doc_mut();
     let f = d.feature_mut(fid).ok_or_else(|| bad(cmd, "the body's feature is gone"))?;
-    while f.body_names.len() <= k {
+    while f.body_names.len() < siblings.len().max(k + 1) {
         let i = f.body_names.len();
         f.body_names.push(siblings.get(i).cloned().unwrap_or_default());
     }
diff --git a/crates/engine/src/tests.rs b/crates/engine/src/tests.rs
index 69b4f930..4cdcc6f6 100644
--- a/crates/engine/src/tests.rs
+++ b/crates/engine/src/tests.rs
@@ -2478,6 +2478,20 @@ fn special_files_are_refused_by_every_file_command() {
     let _ = std::fs::remove_dir_all(&dir);
 }
 
+/// Renaming one pattern copy leaves the other copies' names alone (#265).
+#[test]
+fn renaming_a_pattern_copy_keeps_the_other_copies_names() {
+    let mut s = Session::default();
+    run(&mut s, "solid.box", json!({"length": 10, "width": 10, "height": 10, "operation": "new_body", "body_name": "X"}));
+    run(&mut s, "solid.pattern.rectangular", json!({"bodies": ["X"], "dir1": [1, 0, 0], "count1": 3, "spacing1": 20}));
+    run(&mut s, "body.rename", json!({"body": "X (2)", "name": "Second"}));
+    let third = run(&mut s, "inspect.measure", json!({"bodies": ["X (3)"]}));
+    assert_eq!(third["bodies"][0]["bbox"]["min"][0].as_f64().map(f64::round), Some(40.0), "X (3) is still the copy at x = 40: {third}");
+    run(&mut s, "body.rename", json!({"body": "X (3)", "name": "Third"}));
+    let names: Vec<String> = s.model.state().bodies.iter().map(|b| b.name.clone()).collect();
+    assert_eq!(names, ["X", "Second", "Third"]);
+}
+
 /// Parameters that work are listed in the command's params doc, which is all agents see (#271).
 #[test]
 fn params_docs_list_working_parameters() {