diff --git a/ChangeLog b/ChangeLog
index 2d33641f9..bae9cbadc 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5,6 +5,8 @@ mbed TLS ChangeLog (Sorted per branch, date)
 Bugfix
    * Fix redundant declaration of mbedtls_ssl_list_ciphersuites. Raised by
      TrinityTonic. #1359.
+   * Fix for redefinition of _WIN32_WINNT to avoid overriding a definition
+     used by user applications. Found and fixed by Fabio Alessandrelli.
 
 Changes
    * Support TLS testing in out-of-source builds using cmake. Fixes #1193.
diff --git a/library/net_sockets.c b/library/net_sockets.c
index a1128dc54..1e737c8bb 100644
--- a/library/net_sockets.c
+++ b/library/net_sockets.c
@@ -45,11 +45,12 @@
 #if (defined(_WIN32) || defined(_WIN32_WCE)) && !defined(EFIX64) && \
     !defined(EFI32)
 
-#ifdef _WIN32_WINNT
+#if !defined(_WIN32_WINNT) || (_WIN32_WINNT < 0x0501)
 #undef _WIN32_WINNT
-#endif
 /* Enables getaddrinfo() & Co */
 #define _WIN32_WINNT 0x0501
+#endif
+
 #include <ws2tcpip.h>
 
 #include <winsock2.h>