diff --git a/include/maxscale/cdefs.h b/include/maxscale/cdefs.h
index 3ca29133d..21263b5dc 100644
--- a/include/maxscale/cdefs.h
+++ b/include/maxscale/cdefs.h
@@ -39,6 +39,14 @@
 #undef OPENSSL_THREAD_DEFINES
 #define OPENSSL_THREAD_DEFINES 1
 
+/**
+ * Fix compile errors for PRId64
+ * in Centos 6
+ */
+#ifndef __STDC_FORMAT_MACROS
+# define __STDC_FORMAT_MACROS
+#endif
+
 /**
  * Define intended for use with strerror.
  *