diff --git a/crates/catalog/src/keywords.rs b/crates/catalog/src/keywords.rs
index d351941d6..debdec9d8 100644
--- a/crates/catalog/src/keywords.rs
+++ b/crates/catalog/src/keywords.rs
@@ -32,7 +32,7 @@ pub fn is_under(k: &str, parent: &str) -> bool {
 
 /// Replace the `from` prefix of `k` (which [`is_under`] `from`) with `to`. By levels, not bytes:
 /// `from` may be written in another case, which can change a letter's length (ẞ / ß).
-fn reparent(k: &str, from: &str, to: &str) -> String {
+pub fn reparent(k: &str, from: &str, to: &str) -> String {
     let skip = from.split(SEP).filter(|s| !s.trim().is_empty()).count();
     let rest: Vec<&str> = k.split(SEP).filter(|s| !s.trim().is_empty()).skip(skip).collect();
     std::iter::once(to).filter(|t| !t.is_empty()).chain(rest).collect::<Vec<_>>().join("|")
diff --git a/crates/engine/src/cmd/keywords.rs b/crates/engine/src/cmd/keywords.rs
index 876cf485e..8c21d6579 100644
--- a/crates/engine/src/cmd/keywords.rs
+++ b/crates/engine/src/cmd/keywords.rs
@@ -1,7 +1,7 @@
 //! Library-wide keyword commands: list (tree with counts), suggestions, rename, delete, merge;
 //! keyword sets (nine keywords a keystroke away: ⌥1–⌥9) and Recent Keywords.
 
-use lightcraft_catalog::keywords::{clean, is_under};
+use lightcraft_catalog::keywords::{clean, is_under, reparent};
 use serde_json::{Value, json};
 
 use super::{CommandSpec, always, bad, cmd, str_param};
@@ -197,9 +197,7 @@ pub fn specs() -> Vec<CommandSpec> {
                 let to = str_param(p, "to").ok_or_else(|| bad("keyword.rename", "missing `to`"))?.to_string();
                 let op = s.catalog.rename_keyword_ops(&from, &to).map_err(|e| bad("keyword.rename", e.to_string()))?;
                 let (f, t) = (clean(&from), clean(&to));
-                commit_keywords(s, "Rename Keyword", op, |k| {
-                    Some(if is_under(k, &f) { format!("{t}{}", &k[f.len().min(k.len())..]) } else { k.to_string() })
-                })
+                commit_keywords(s, "Rename Keyword", op, |k| Some(if is_under(k, &f) { reparent(k, &f, &t) } else { k.to_string() }))
             }
         ),
         cmd!(
@@ -230,7 +228,7 @@ pub fn specs() -> Vec<CommandSpec> {
                 let (from, into) = (from.iter().map(|f| clean(f)).collect::<Vec<_>>(), clean(&into));
                 commit_keywords(s, "Merge Keywords", op, |k| {
                     Some(match from.iter().find(|f| is_under(k, f)) {
-                        Some(f) => format!("{into}{}", &k[f.len().min(k.len())..]),
+                        Some(f) => reparent(k, f, &into),
                         None => k.to_string(),
                     })
                 })
diff --git a/crates/engine/src/lib.rs b/crates/engine/src/lib.rs
index a6c5f6420..aab6c0277 100644
--- a/crates/engine/src/lib.rs
+++ b/crates/engine/src/lib.rs
@@ -859,6 +859,8 @@ mod tests_import;
 #[cfg(test)]
 mod tests_import_move;
 #[cfg(test)]
+mod tests_keyword_list;
+#[cfg(test)]
 mod tests_libops;
 #[cfg(test)]
 mod tests_library;
diff --git a/crates/engine/src/tests_keyword_list.rs b/crates/engine/src/tests_keyword_list.rs
new file mode 100644
index 000000000..04a78fa8c
--- /dev/null
+++ b/crates/engine/src/tests_keyword_list.rs
@@ -0,0 +1,21 @@
+//! The keyword list's commands (Lightroom Classic's Keyword List): create, edit, move and purge
+//! keywords, their attributes, and the default parent for new keywords.
+
+use serde_json::json;
+
+use crate::Session;
+
+/// The keyword filter follows a renamed keyword whatever the case it was typed in, also where a
+/// letter's case changes its length (ẞ / ß): it used to be cut by bytes, which could land inside
+/// a letter and panic.
+#[test]
+fn the_filter_follows_a_rename_whatever_the_case() {
+    let mut s = Session::with_demo();
+    let id = s.visible_cloned()[0].0;
+    s.execute("photo.setMeta", &json!({"ids": [id], "keywords": ["ßßa|é"]})).unwrap();
+    s.execute("library.filter", &json!({"keyword": "ßßa|é"})).unwrap();
+    s.execute("keyword.rename", &json!({"from": "ẞẞA", "to": "Road"})).unwrap();
+    assert_eq!(s.filter.keyword.as_deref(), Some("Road|é"));
+    s.execute("keyword.merge", &json!({"from": ["ROAD"], "into": "Weg"})).unwrap();
+    assert_eq!(s.filter.keyword.as_deref(), Some("Weg|é"));
+}