diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index 8d377d0..6d5d289 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -36,6 +36,26 @@ jobs:
       - name: Verify completion files are up to date
         run: ./scripts/generate-completions.sh --check
 
+  bash-compatibility:
+    name: macOS Bash 3.2
+    runs-on: macos-latest
+    steps:
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+        with:
+          persist-credentials: false
+
+      - name: Exercise CLI startup and shell integration with system Bash
+        shell: /bin/bash --noprofile --norc -eo pipefail {0}
+        run: |
+          export PATH="$PWD/bin:/usr/bin:/bin:/usr/sbin:/sbin:$PATH"
+          export XDG_CACHE_HOME="$RUNNER_TEMP/gtr-cache"
+          /bin/bash --version
+          git gtr --version
+          ./bin/gtr --version
+          git gtr init bash > "$RUNNER_TEMP/gtr-init.bash"
+          /bin/bash -n "$RUNNER_TEMP/gtr-init.bash"
+          source "$RUNNER_TEMP/gtr-init.bash"
+
   test:
     name: Tests
     runs-on: ubuntu-latest
diff --git a/lib/commands/init.sh b/lib/commands/init.sh
index 77e75b3..96f9521 100644
--- a/lib/commands/init.sh
+++ b/lib/commands/init.sh
@@ -135,6 +135,7 @@ _init_emit_posix_trust_helpers() {
   # Keep the snapshot encoding and extraction identical to the CLI.
   _init_emit_snapshot_helpers
 
+  # Keep case patterns balanced inside this substitution for Bash 3.2's parser.
   template=$(cat <<'EOF'
 __FUNC___gtrconfig_path() {
 __SHELL_PRELUDE__
@@ -186,7 +187,7 @@ __SHELL_PRELUDE__
   _gtr_birth_time="${_gtr_identity#*:*:}"
   _gtr_birth_time="${_gtr_birth_time%%:*}"
   case "$_gtr_birth_time" in
-    ''|0|0.*|*[!0-9.]*) return 1 ;;
+    (''|0|0.*|*[!0-9.]*) return 1 ;;
   esac
   printf '%s\n%s\n' "$_gtr_common_dir" "$_gtr_identity"
 }