diff --git a/src/vppinfra/clib.h b/src/vppinfra/clib.h
index 05af8fe..4629a7d 100644
--- a/src/vppinfra/clib.h
+++ b/src/vppinfra/clib.h
@@ -120,6 +120,7 @@
 /* Hints to compiler about hot/cold code. */
 #define PREDICT_FALSE(x) __builtin_expect((x),0)
 #define PREDICT_TRUE(x) __builtin_expect((x),1)
+#define COMPILE_TIME_CONST(x) __builtin_constant_p (x)
 
 /*
  * Compiler barrier
diff --git a/src/vppinfra/string.h b/src/vppinfra/string.h
index fb46a0c..76d345e 100644
--- a/src/vppinfra/string.h
+++ b/src/vppinfra/string.h
@@ -143,7 +143,7 @@
    * Optimize constant-number-of-bytes calls without asking
    * "too many questions for someone from New Jersey"
    */
-  if (__builtin_constant_p (n))
+  if (COMPILE_TIME_CONST (n))
     {
       clib_memcpy_fast (dest, src, n);
       return EOK;