diff --git a/cr_generate_id.c b/cr_generate_id.c
index bf75416..9547787 100644
--- a/cr_generate_id.c
+++ b/cr_generate_id.c
@@ -128,7 +128,7 @@
 #include <openssl/ec.h>
 #include <openssl/rsa.h>
 #include <openssl/aes.h>
-#include <openssl/X509.h>
+#include <openssl/x509.h>
 
 #include "ec_lcl.h"	// ec_key_st構造体の参照に必要
 #include "openssl-0.9.8k/crypto/pem/pem.h"	// for PEM_read_X509 関数