diff --git a/src/bio.c b/src/bio.c
index db6d85d577..e8e66597e6 100644
--- a/src/bio.c
+++ b/src/bio.c
@@ -24,10 +24,9 @@
 #endif
 
 #include <wolfssl/wolfcrypt/settings.h>
-#if defined(OPENSSL_EXTRA) && !defined(_WIN32)
+#if defined(OPENSSL_EXTRA) && !defined(_WIN32) && !defined(_GNU_SOURCE)
     /* turn on GNU extensions for XVASPRINTF with wolfSSL_BIO_printf */
-    #undef  _GNU_SOURCE
-    #define _GNU_SOURCE
+    #define _GNU_SOURCE 1
 #endif
 
 #if !defined(WOLFSSL_BIO_INCLUDED)
diff --git a/src/ssl.c b/src/ssl.c
index 8affb043a4..fd8a8f0128 100644
--- a/src/ssl.c
+++ b/src/ssl.c
@@ -25,10 +25,9 @@
 #endif
 
 #include <wolfssl/wolfcrypt/settings.h>
-#if defined(OPENSSL_EXTRA) && !defined(_WIN32)
+#if defined(OPENSSL_EXTRA) && !defined(_WIN32) && !defined(_GNU_SOURCE)
     /* turn on GNU extensions for XISASCII */
-    #undef  _GNU_SOURCE
-    #define _GNU_SOURCE
+    #define _GNU_SOURCE 1
 #endif
 
 #if !defined(WOLFCRYPT_ONLY) || defined(OPENSSL_EXTRA) || \
diff --git a/wolfssl/openssl/opensslv.h b/wolfssl/openssl/opensslv.h
index 8d36ea24c7..481f74ee39 100644
--- a/wolfssl/openssl/opensslv.h
+++ b/wolfssl/openssl/opensslv.h
@@ -34,7 +34,10 @@
     defined(OPENSSL_VERSION_NUMBER) && (OPENSSL_VERSION_NUMBER == 0x0090810fL) ||\
     defined(OPENSSL_VERSION_NUMBER) && (OPENSSL_VERSION_NUMBER == 0x10100000L) ||\
     defined(OPENSSL_VERSION_NUMBER) && (OPENSSL_VERSION_NUMBER == 0x10001040L)
-     /* valid version */
+    /* valid version */
+#elif defined(OPENSSL_VERSION_NUMBER)
+    /* unrecognized version, but continue. */
+    #define WOLFSSL_OPENSSL_VERSION_NUMBER_UNRECOGNIZED
 #elif defined(HAVE_MOSQUITTO)
     #define OPENSSL_VERSION_NUMBER 0x10100000L
 #elif defined(WOLFSSL_APACHE_HTTPD) || defined(HAVE_LIBEST) || \
@@ -57,11 +60,15 @@
     #define OPENSSL_VERSION_NUMBER 0x0090810fL
 #endif
 
-#define OPENSSL_VERSION_TEXT             "wolfSSL " LIBWOLFSSL_VERSION_STRING
-#define OPENSSL_VERSION                  0
+#ifndef OPENSSL_VERSION_TEXT
+    #define OPENSSL_VERSION_TEXT "wolfSSL " LIBWOLFSSL_VERSION_STRING
+#endif
+#ifndef OPENSSL_VERSION
+    #define OPENSSL_VERSION 0
+#endif
 
 #ifndef OPENSSL_IS_WOLFSSL
-#define OPENSSL_IS_WOLFSSL
+    #define OPENSSL_IS_WOLFSSL
 #endif
 
 #endif /* OPENSSL_EXTRA || OPENSSL_EXTRA_X509_SMALL */