diff --git a/ChangeLog b/ChangeLog
index 027a97174..517381bc5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 mbed TLS ChangeLog (Sorted per branch, date)
 
+= mbed TLS x.x.x branch released xxxx-xx-xx
+
+Changes
+   * Allow overriding the time on Windows via the platform-time abstraction.
+     Fixed by Nick Wilson.
+   * Use gmtime_r/gmtime_s for thread-safety. Fixed by Nick Wilson.
+
 = mbed TLS 2.11.0 branch released 2018-06-18
 
 Features
diff --git a/include/mbedtls/threading.h b/include/mbedtls/threading.h
index aeea5d0e1..c25daa5cd 100644
--- a/include/mbedtls/threading.h
+++ b/include/mbedtls/threading.h
@@ -99,9 +99,6 @@ extern int (*mbedtls_mutex_unlock)( mbedtls_threading_mutex_t *mutex );
 #if defined(MBEDTLS_FS_IO)
 extern mbedtls_threading_mutex_t mbedtls_threading_readdir_mutex;
 #endif
-#if defined(MBEDTLS_HAVE_TIME_DATE)
-extern mbedtls_threading_mutex_t mbedtls_threading_gmtime_mutex;
-#endif
 #endif /* MBEDTLS_THREADING_C */
 
 #ifdef __cplusplus
diff --git a/library/threading.c b/library/threading.c
index f1c37245c..7a32e672c 100644
--- a/library/threading.c
+++ b/library/threading.c
@@ -114,9 +114,6 @@ void mbedtls_threading_set_alt( void (*mutex_init)( mbedtls_threading_mutex_t *
 #if defined(MBEDTLS_FS_IO)
     mbedtls_mutex_init( &mbedtls_threading_readdir_mutex );
 #endif
-#if defined(MBEDTLS_HAVE_TIME_DATE)
-    mbedtls_mutex_init( &mbedtls_threading_gmtime_mutex );
-#endif
 }
 
 /*
@@ -127,9 +124,6 @@ void mbedtls_threading_free_alt( void )
 #if defined(MBEDTLS_FS_IO)
     mbedtls_mutex_free( &mbedtls_threading_readdir_mutex );
 #endif
-#if defined(MBEDTLS_HAVE_TIME_DATE)
-    mbedtls_mutex_free( &mbedtls_threading_gmtime_mutex );
-#endif
 }
 #endif /* MBEDTLS_THREADING_ALT */
 
@@ -142,8 +136,5 @@ void mbedtls_threading_free_alt( void )
 #if defined(MBEDTLS_FS_IO)
 mbedtls_threading_mutex_t mbedtls_threading_readdir_mutex MUTEX_INIT;
 #endif
-#if defined(MBEDTLS_HAVE_TIME_DATE)
-mbedtls_threading_mutex_t mbedtls_threading_gmtime_mutex MUTEX_INIT;
-#endif
 
 #endif /* MBEDTLS_THREADING_C */
diff --git a/library/x509.c b/library/x509.c
index 371d6da1d..906d1714b 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -59,14 +59,10 @@
 #define mbedtls_snprintf  snprintf
 #endif
 
-
 #if defined(MBEDTLS_HAVE_TIME)
 #include "mbedtls/platform_time.h"
 #endif
-
-#if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
-#include <windows.h>
-#else
+#if defined(MBEDTLS_HAVE_TIME_DATE)
 #include <time.h>
 #endif
 
@@ -903,36 +899,18 @@ int mbedtls_x509_key_size_helper( char *buf, size_t buf_size, const char *name )
  * Set the time structure to the current time.
  * Return 0 on success, non-zero on failure.
  */
-#if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
 static int x509_get_current_time( mbedtls_x509_time *now )
 {
-    SYSTEMTIME st;
-
-    GetSystemTime( &st );
-
-    now->year = st.wYear;
-    now->mon  = st.wMonth;
-    now->day  = st.wDay;
-    now->hour = st.wHour;
-    now->min  = st.wMinute;
-    now->sec  = st.wSecond;
-
-    return( 0 );
-}
-#else
-static int x509_get_current_time( mbedtls_x509_time *now )
-{
-    struct tm *lt;
+    struct tm *lt, tm_buf;
     mbedtls_time_t tt;
     int ret = 0;
 
-#if defined(MBEDTLS_THREADING_C)
-    if( mbedtls_mutex_lock( &mbedtls_threading_gmtime_mutex ) != 0 )
-        return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
-#endif
-
     tt = mbedtls_time( NULL );
-    lt = gmtime( &tt );
+#if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
+    lt = gmtime_s( &tm_buf, &tt ) == 0 ? &tm_buf : NULL;
+#else
+    lt = gmtime_r( &tt, &tm_buf );
+#endif
 
     if( lt == NULL )
         ret = -1;
@@ -946,14 +924,8 @@ static int x509_get_current_time( mbedtls_x509_time *now )
         now->sec  = lt->tm_sec;
     }
 
-#if defined(MBEDTLS_THREADING_C)
-    if( mbedtls_mutex_unlock( &mbedtls_threading_gmtime_mutex ) != 0 )
-        return( MBEDTLS_ERR_THREADING_MUTEX_ERROR );
-#endif
-
     return( ret );
 }
-#endif /* _WIN32 && !EFIX64 && !EFI32 */
 
 /*
  * Return 0 if before <= after, 1 otherwise