diff --git a/include/haproxy/compiler.h b/include/haproxy/compiler.h
index dbfcb6228..fcf0d9306 100644
--- a/include/haproxy/compiler.h
+++ b/include/haproxy/compiler.h
@@ -27,7 +27,7 @@
  * Gcc before 3.0 needs [0] to declare a variable-size array
  */
 #ifndef VAR_ARRAY
-#if  __GNUC__  < 3
+#if defined(__GNUC__) && (__GNUC__ < 3)
 #define VAR_ARRAY	0
 #else
 #define VAR_ARRAY
@@ -39,7 +39,7 @@
  * respect our choices.
  */
 #if !defined(forceinline)
-#if __GNUC__ < 3
+#if !defined(__GNUC__) || (__GNUC__ < 3)
 #define forceinline inline
 #else
 #define forceinline inline __attribute__((always_inline))
@@ -89,7 +89,7 @@
  * generally better for the cache and to reduce the number of jumps.
  */
 #if !defined(likely)
-#if __GNUC__ < 3
+#if !defined(__GNUC__) || (__GNUC__ < 3)
 #define __builtin_expect(x,y) (x)
 #define likely(x) (x)
 #define unlikely(x) (x)