diff --git a/ext/bz2/bz2_filter.c b/ext/bz2/bz2_filter.c
index fc28823d37c..441c1d1d7cd 100644
--- a/ext/bz2/bz2_filter.c
+++ b/ext/bz2/bz2_filter.c
@@ -18,6 +18,10 @@
 
 /* $Id$ */
 
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
 #include "php.h"
 #include "php_bz2.h"