diff --git a/cli/build.rs b/cli/build.rs
index 76feac9548..ec5119d762 100644
--- a/cli/build.rs
+++ b/cli/build.rs
@@ -44,8 +44,8 @@ fn main() -> std::io::Result<()> {
     }
     println!("cargo:rerun-if-env-changed=NIX_JJ_GIT_HASH");
 
-    // TODO: timestamp can be "nix"
-    if let Some((git_hash, maybe_date)) = get_git_timestamp_and_hash() {
+    if let Some((mut git_hash, maybe_date)) = get_git_timestamp_and_hash() {
+        git_hash.truncate(16);
         println!(
             "cargo:rustc-env=JJ_VERSION={}-{}-{}",
             version,
diff --git a/cli/tests/test_global_opts.rs b/cli/tests/test_global_opts.rs
index 2d6223fb4d..fb6ad80ba1 100644
--- a/cli/tests/test_global_opts.rs
+++ b/cli/tests/test_global_opts.rs
@@ -48,9 +48,9 @@ fn test_version() {
     let sanitized = stdout.replace(|c: char| c.is_ascii_hexdigit(), "?");
     let expected = [
         "jj ?.??.?\n",
-        "jj ?.??.?-????????-????????????????????????????????????????\n",
+        "jj ?.??.?-????????-????????????????\n",
         // `dateunknown` turns into `??t?unknown` since d,a,e are hex digits.
-        "jj ?.??.?-??t?unknown-????????????????????????????????????????\n",
+        "jj ?.??.?-??t?unknown-????????????????\n",
     ];
     assert!(
         expected.contains(&sanitized.as_str()),