diff --git a/docs/config.md b/docs/config.md
index 2d0885960..a1ebc4c8a 100644
--- a/docs/config.md
+++ b/docs/config.md
@@ -152,6 +152,15 @@ Can be customized by the `format_short_id()` template alias.
 'format_short_id(id)' = 'id.short(12)'
 ```
 
+To customize these separately, use the `format_short_commit_id()` and
+`format_short_change_id()` aliases:
+
+```toml
+[template-aliases]
+# Uppercase change ids. `jj` treats change and commit ids as case-insensitive.
+'format_short_change_id(id)' = 'format_short_id(id).upper()'
+```
+
 ### Relative timestamps
 
 Can be customized by the `format_timestamp()` template alias.
diff --git a/src/config/templates.toml b/src/config/templates.toml
index e964a24cc..33978a350 100644
--- a/src/config/templates.toml
+++ b/src/config/templates.toml
@@ -1,6 +1,6 @@
 [templates]
 commit_summary = '''
-format_short_id(commit_id) " "
+format_short_commit_id(commit_id) " "
 if(description, description.first_line(), description_placeholder)
 '''
 
@@ -8,15 +8,15 @@ log = '''
 label(if(current_working_copy, "working_copy"),
   separate(" ",
     if(divergent,
-      label("divergent", format_short_id(change_id) "??"),
-      format_short_id(change_id)),
+      label("divergent", format_short_change_id(change_id) "??"),
+      format_short_change_id(change_id)),
     format_short_signature(author),
     format_timestamp(committer.timestamp()),
     branches,
     tags,
     working_copies,
     git_head,
-    format_short_id(commit_id),
+    format_short_commit_id(commit_id),
     if(conflict, label("conflict", "conflict")),
   )
   "\n"
@@ -47,6 +47,8 @@ show = 'show'
 
 # Hook points for users to customize the default templates:
 'format_short_id(id)' = 'id.shortest(12)'
+'format_short_change_id(id)' = 'format_short_id(id)'
+'format_short_commit_id(id)' = 'format_short_id(id)'
 'format_short_signature(signature)' = 'signature.email()'
 'format_time_range(time_range)' = '''
   time_range.start().ago() label("time", ", lasted ") time_range.duration()'''
diff --git a/tests/test_commit_template.rs b/tests/test_commit_template.rs
index c95961f2b..8f90eb968 100644
--- a/tests/test_commit_template.rs
+++ b/tests/test_commit_template.rs
@@ -177,15 +177,39 @@ fn test_log_customize_short_id() {
 
     test_env.jj_cmd_success(&repo_path, &["describe", "-m", "first"]);
 
+    // Customize both the commit and the change id
     let decl = "template-aliases.'format_short_id(id)'";
     let stdout = test_env.jj_cmd_success(
         &repo_path,
-        &["log", "--config-toml", &format!("{decl}='id.shortest()'")],
+        &[
+            "log",
+            "--config-toml",
+            &format!("{decl}='id.shortest(5).prefix().upper() \"_\" id.shortest(5).rest()'"),
+        ],
     );
     insta::assert_snapshot!(stdout, @r###"
-    @  q test.user@example.com 2001-02-03 04:05:08.000 +07:00 6
+    @  Q_pvun test.user@example.com 2001-02-03 04:05:08.000 +07:00 6_9542
     │  (empty) first
-    o  z 1970-01-01 00:00:00.000 +00:00 0
+    o  Z_zzzz 1970-01-01 00:00:00.000 +00:00 0_0000
+       (empty) (no description set)
+    "###);
+
+    // Customize only the change id
+    let stdout = test_env.jj_cmd_success(
+        &repo_path,
+        &[
+            "log",
+            "--config-toml",
+            r#"
+                [template-aliases]
+                'format_short_change_id(id)'='format_short_id(id).upper()'
+            "#,
+        ],
+    );
+    insta::assert_snapshot!(stdout, @r###"
+    @  QPVUNTSMWLQT test.user@example.com 2001-02-03 04:05:08.000 +07:00 69542c1984c1
+    │  (empty) first
+    o  ZZZZZZZZZZZZ 1970-01-01 00:00:00.000 +00:00 000000000000
        (empty) (no description set)
     "###);
 }