Index: gen_dh_params
==================================================================
--- gen_dh_params
+++ gen_dh_params
@@ -74,11 +74,11 @@
 	}
 
 	dhp_bn = BN_bin2bn(dhp_2048, sizeof (dhp_2048), NULL);
 	dhg_bn = BN_bin2bn(dhg_2048, sizeof (dhg_2048), NULL);
 
-#if OPENSSL_VERSION_NUMBER < 0x10100000L
+#ifdef TCLTLS_OPENSSL_PRE_1_1_API
 	dh->p = dhp_bn;
 	dh->g = dhg_bn;
 
 	if (dhp_bn == NULL || dhg_bn == NULL) {
 #else

Index: tlsBIO.c
==================================================================
--- tlsBIO.c
+++ tlsBIO.c
@@ -4,11 +4,11 @@
  * Provides BIO layer to interface openssl to Tcl.
  */
 
 #include "tlsInt.h"
 
-#if OPENSSL_VERSION_NUMBER < 0x10100000L
+#ifdef TCLTLS_OPENSSL_PRE_1_1_API
 #define BIO_get_data(bio)                ((bio)->ptr)
 #define BIO_get_init(bio)                ((bio)->init)
 #define BIO_get_shutdown(bio)            ((bio)->shutdown)
 #define BIO_set_data(bio, val)           (bio)->ptr = (val)
 #define BIO_set_init(bio, val)           (bio)->init = (val)

Index: tlsInt.h
==================================================================
--- tlsInt.h
+++ tlsInt.h
@@ -53,20 +53,16 @@
 #include <openssl/err.h>
 #include <openssl/rand.h>
 #include <openssl/opensslv.h>
 #endif
 
-#ifndef NO_TLS1_1
-#  ifndef SSL_OP_NO_TLSv1_1
-#    define NO_TLS1_1
-#  endif
-#endif
-
-#ifndef NO_TLS1_2
-#  ifndef SSL_OP_NO_TLSv1_2
-#    define NO_TLS1_2
-#  endif
+/*
+ * Determine if we should use the pre-OpenSSL 1.1.0 API
+ */
+#undef TCLTLS_OPENSSL_PRE_1_1
+#if (defined(LIBRESSL_VERSION_NUMBER)) || OPENSSL_VERSION_NUMBER < 0x10100000L
+#  define TCLTLS_OPENSSL_PRE_1_1_API 1
 #endif
 
 #ifdef TCL_STORAGE_CLASS
 # undef TCL_STORAGE_CLASS
 #endif