diff --git a/extras/mini-os/include/compiler.h b/extras/mini-os/include/compiler.h
index e35c9d50ff..41882774f9 100644
--- a/extras/mini-os/include/compiler.h
+++ b/extras/mini-os/include/compiler.h
@@ -1,5 +1,10 @@
+#ifndef __MINIOS_COMPILER_H_
+#define __MINIOS_COMPILER_H_
+
 #if __GNUC__ == 2 && __GNUC_MINOR__ < 96
 #define __builtin_expect(x, expected_value) (x)
 #endif
-#define unlikely(x)  __builtin_expect((x),0)
-#define likely(x)  __builtin_expect((x),1)
+#define unlikely(x)  __builtin_expect(!!(x),0)
+#define likely(x)    __builtin_expect(!!(x),1)
+
+#endif /* __MINIOS_COMPILER_H_ */