diff --git a/sapi/apache2filter/php_functions.c b/sapi/apache2filter/php_functions.c
index 1ab9e6f6512..a26d6ad5272 100644
--- a/sapi/apache2filter/php_functions.c
+++ b/sapi/apache2filter/php_functions.c
@@ -23,6 +23,7 @@
 #include "ext/standard/info.h"
 #include "SAPI.h"
 
+#define CORE_PRIVATE
 #include "apr_strings.h"
 #include "apr_time.h"
 #include "ap_config.h"