diff --git a/.claude/skills/grok/scripts/ask-grok.sh b/.claude/skills/grok/scripts/ask-grok.sh
index e0d534f..70144aa 100644
--- a/.claude/skills/grok/scripts/ask-grok.sh
+++ b/.claude/skills/grok/scripts/ask-grok.sh
@@ -72,9 +72,15 @@ REPO_ROOT="${CLAUDETOOLS_ROOT:-$(cd "$SCRIPT_DIR/../../../.." 2>/dev/null && pwd
 
 # run grok headless. $1=timeout secs; rest=extra flags. Reads $PF -> $OUT.
 # Never fails the script on grok's exit code (Cancelled is expected; we read artifacts).
+# Use gtimeout on macOS (from brew coreutils), timeout on Linux/Windows.
+TIMEOUT_CMD="timeout"
+if [[ "$OSTYPE" == "darwin"* ]]; then
+  TIMEOUT_CMD="$(command -v gtimeout 2>/dev/null || echo timeout)"
+fi
+
 run_grok() {
   local to="$1"; shift
-  timeout "$to" "$GROK" --prompt-file "$PF" --output-format json \
+  "$TIMEOUT_CMD" "$to" "$GROK" --prompt-file "$PF" --output-format json \
     --permission-mode dontAsk --no-subagents --no-plan --cwd "$RUN_CWD" "$@" \
     >"$OUT" 2>"$TMP/err.txt" || true
 }