diff --git a/examples/cpp/lib/effect.h b/examples/cpp/lib/effect.h
index 4438cbada4bb5ea7c447f4f8e64f10c0623dcd40..66330afba16e55791702600d8ba05df9124f4595 100644
--- a/examples/cpp/lib/effect.h
+++ b/examples/cpp/lib/effect.h
@@ -307,3 +307,9 @@ inline int EffectRunner::usage(const char *name)
     fprintf(stderr, "usage: %s [-fps LIMIT] [-layout FILE.json] [-server HOST[:port]]\n", name);
     return 1;
 }
+
+static inline float sq(float a)
+{
+    // Fast square
+    return a*a;
+}