diff --git a/include/common/regex.h b/include/common/regex.h
index 0104019..1cc471b 100644
--- a/include/common/regex.h
+++ b/include/common/regex.h
@@ -22,6 +22,8 @@
 #ifndef _COMMON_REGEX_H
 #define _COMMON_REGEX_H
 
+#include <stdlib.h>
+
 #include <common/config.h>
 
 #ifdef USE_PCRE