-#define HAVE_TLS
-#include <openssl/crypto.h>
-#include <openssl/x509.h>
-#include <openssl/pem.h>
-#include <openssl/ssl.h>
-#include <openssl/err.h>
-#include <openssl/rand.h>
-#include <openssl/ocsp.h>
+# define HAVE_TLS
+# include <openssl/crypto.h>
+# include <openssl/x509.h>
+# include <openssl/pem.h>
+# include <openssl/ssl.h>
+# include <openssl/err.h>
+# include <openssl/rand.h>
+
+# if OPENSSL_VERSION_NUMBER < 0x0090806fL && !defined(DISABLE_OCSP) && !defined(OPENSSL_NO_TLSEXT)
+# warning "OpenSSL library version too old; define DISABLE_OCSP in Makefile"
+# define DISABLE_OCSP
+# endif
+# ifndef DISABLE_OCSP
+# include <openssl/ocsp.h>
+# endif