diff --git a/test/v3ext.c b/test/v3ext.c
index 386135fed8ab1..7a240cd706034 100644
--- a/test/v3ext.c
+++ b/test/v3ext.c
@@ -8,6 +8,7 @@
  */
 
 #include <stdio.h>
+#include <string.h>
 #include <openssl/x509.h>
 #include <openssl/x509v3.h>
 #include <openssl/pem.h>