diff --git a/.woodpecker/agent-smoke.sh b/.woodpecker/agent-smoke.sh
index 0d2a016..2e8eb9c 100644
--- a/.woodpecker/agent-smoke.sh
+++ b/.woodpecker/agent-smoke.sh
@@ -21,9 +21,12 @@ FAILED=0
 # Uses awk instead of grep -Eo for busybox/Alpine compatibility (#296).
 get_fns() {
   local f="$1"
-  awk '/^[ \t]*[a-zA-Z_][a-zA-Z0-9_]+[ \t]*\(\)/ {
-    sub(/^[ \t]+/, "")
-    sub(/[ \t]*\(\).*/, "")
+  # Use POSIX character classes and bracket-escaped parens for BusyBox awk
+  # compatibility (BusyBox awk does not expand \t to tab in character classes
+  # and may handle \( differently in ERE patterns).
+  awk '/^[[:space:]]*[a-zA-Z_][a-zA-Z0-9_]+[[:space:]]*[(][)]/ {
+    sub(/^[[:space:]]+/, "")
+    sub(/[[:space:]]*[(][)].*/, "")
     print
   }' "$f" 2>/dev/null | sort -u || true
 }