diff --git a/cli/build.rs b/cli/build.rs
index 0433ed3f0d..e41931e792 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((maybe_date, git_hash)) = get_git_timestamp_and_hash() {
+    if let Some((maybe_date, mut git_hash)) = 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 ac81a843e4..8b9bdd1c8b 100644
--- a/cli/tests/test_global_opts.rs
+++ b/cli/tests/test_global_opts.rs
@@ -72,9 +72,9 @@ fn test_no_subcommand() {
     assert_matches!(
         sanitized.as_str(),
         "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"
     );
 
     let stdout = test_env.jj_cmd_success(test_env.env_root(), &["-R", "repo"]);