diff --git a/crypto/conf/conf_api.c b/crypto/conf/conf_api.c
index d05a778ff6..a42c21970a 100644
--- a/crypto/conf/conf_api.c
+++ b/crypto/conf/conf_api.c
@@ -67,6 +67,7 @@
 #include <string.h>
 #include <openssl/conf.h>
 #include <openssl/conf_api.h>
+#include "e_os.h"
 
 static void value_free_hash(CONF_VALUE *a, LHASH *conf);
 static void value_free_stack(CONF_VALUE *a,LHASH *conf);