diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 226190de0..0d5d9d017 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -137,7 +137,7 @@
 /**
  * \def MBEDTLS_HAVE_TIME_DATE
  *
- * System has time.h, time(), an implementation for mbedtls_platform_gmtime()
+ * System has time.h, time(), an implementation for mbedtls_platform_gmtime_r()
  * (see below), and the clock is correct.
  * The time needs to be correct (not necesarily very accurate, but at least
  * the date should be correct). This is used to verify the validity period of
@@ -145,17 +145,17 @@
  *
  * Comment if your system does not have a correct clock.
  *
- * \note mbedtls_platform_gmtime() is an abstraction in platform_util.h that
+ * \note mbedtls_platform_gmtime_r() is an abstraction in platform_util.h that
  * when called behaves similarly to the gmtime() function from the C standard,
  * but is thread safe. Mbed TLS will try to identify the underlying platform
  * and configure an appropriate underlying implementation (e.g. gmtime_r() for
  * POSIX and gmtime_s() for Windows). If this is not possible, then
  * gmtime() will be used. Refer to the documentation for
- * mbedtls_platform_gmtime() for more information.
+ * mbedtls_platform_gmtime_r() for more information.
  *
  * \note It is possible to configure an implementation for
- * mbedtls_platform_gmtime() at compile-time by using the macro
- * MBEDTLS_PLATFORM_GMTIME_ALT.
+ * mbedtls_platform_gmtime_r() at compile-time by using the macro
+ * MBEDTLS_PLATFORM_GMTIME_R_ALT.
  */
 #define MBEDTLS_HAVE_TIME_DATE
 
@@ -3098,22 +3098,22 @@
 
 /**
  * Uncomment the macro to let Mbed TLS use your alternate implementation of
- * mbedtls_platform_gmtime(). This replaces the default implementation in
+ * mbedtls_platform_gmtime_r(). This replaces the default implementation in
  * platform_util.c.
  *
  * gmtime() is not a thread safe function as defined in the C standard. The
  * library will try to use safer implementations of this function, such as
  * gmtime_r() when available. However, if Mbed TLS cannot identify the target
- * system, the implementation of mbedtls_platform_gmtime() will default to
+ * system, the implementation of mbedtls_platform_gmtime_r() will default to
  * using the standard gmtime(). In this case, calls from the library to
  * gmtime() will be guarded by the global mutex mbedtls_threading_gmtime_mutex
  * if MBEDTLS_THREADING_C is enable. It is advised that calls from outside the
  * library are also guarded with this mutex to avoid race conditions. However,
- * if the macro MBEDTLS_PLATFORM_GMTIME_ALT is defined, Mbed TLS will
- * unconditionally use the implementation for mbedtls_platform_time() supplied
- * at compile time.
+ * if the macro MBEDTLS_PLATFORM_GMTIME_R_ALT is defined, Mbed TLS will
+ * unconditionally use the implementation for mbedtls_platform_gmtime_r()
+ * supplied at compile time.
  */
-//#define MBEDTLS_PLATFORM_GMTIME_ALT
+//#define MBEDTLS_PLATFORM_GMTIME_R_ALT
 
 /* \} name SECTION: Customisation configuration options */
 
diff --git a/include/mbedtls/platform_util.h b/include/mbedtls/platform_util.h
index befd3344c..ca42adf6e 100644
--- a/include/mbedtls/platform_util.h
+++ b/include/mbedtls/platform_util.h
@@ -68,24 +68,24 @@ void mbedtls_platform_zeroize( void *buf, size_t len );
 
 #if defined(MBEDTLS_HAVE_TIME_DATE)
 /**
- * \brief       Thread safe implementation of gmtime()
+ * \brief      Thread safe implementation of gmtime()
  *
- *              The function is an abstraction that when called behaves similar
- *              to the gmtime() function from the C standard, but is thread
- *              safe.
+ *             The function is an abstraction that when called behaves similar
+ *             to the gmtime() function from the C standard, but is thread
+ *             safe.
  *
- *              Mbed TLS will try to identify the underlying platform and
- *              configure an appropriate underlying implementation (e.g.
- *              gmtime_r() for POSIX and gmtime_s() for Windows). If this is
- *              not possible, then gmtime() will be used. In this case, calls
- *              from the library to gmtime() will be guarded by the mutex
- *              mbedtls_threading_gmtime_mutex if MBEDTLS_THREADING_C is
- *              enabled. It is recommended that calls from outside the library
- *              are also guarded by this mutex.
+ *             Mbed TLS will try to identify the underlying platform and
+ *             configure an appropriate underlying implementation (e.g.
+ *             gmtime_r() for POSIX and gmtime_s() for Windows). If this is
+ *             not possible, then gmtime() will be used. In this case, calls
+ *             from the library to gmtime() will be guarded by the mutex
+ *             mbedtls_threading_gmtime_mutex if MBEDTLS_THREADING_C is
+ *             enabled. It is recommended that calls from outside the library
+ *             are also guarded by this mutex.
  *
- *              If MBEDTLS_PLATFORM_GMTIME_ALT is defined, then Mbed TLS will
- *              unconditionally use the alternative implementation for
- *              mbedtls_platform_gmtime() supplied by the user at compile time
+ *             If MBEDTLS_PLATFORM_GMTIME_R_ALT is defined, then Mbed TLS will
+ *             unconditionally use the alternative implementation for
+ *             mbedtls_platform_gmtime_r() supplied by the user at compile time.
  *
  * \param tt     Pointer to an object containing time (in seconds) since the
  *               Epoc to be converted
@@ -94,8 +94,8 @@ void mbedtls_platform_zeroize( void *buf, size_t len );
  * \return      Pointer to an object of type struct tm on success, otherwise
  *              NULL
  */
-struct tm *mbedtls_platform_gmtime( const mbedtls_time_t *tt,
-                                    struct tm *tm_buf );
+struct tm *mbedtls_platform_gmtime_r( const mbedtls_time_t *tt,
+                                      struct tm *tm_buf );
 #endif /* MBEDTLS_HAVE_TIME_DATE */
 
 #ifdef __cplusplus
diff --git a/include/mbedtls/threading.h b/include/mbedtls/threading.h
index 9235a1e98..66f78f5b5 100644
--- a/include/mbedtls/threading.h
+++ b/include/mbedtls/threading.h
@@ -107,7 +107,7 @@ 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) && !defined(MBEDTLS_PLATFORM_GMTIME_ALT)
+#if defined(MBEDTLS_HAVE_TIME_DATE) && !defined(MBEDTLS_PLATFORM_GMTIME_R_ALT)
 #if !defined(_WIN32) && (defined(unix) || \
     defined(__unix) || defined(__unix__) || (defined(__APPLE__) && \
     defined(__MACH__)))
@@ -122,7 +122,7 @@ extern mbedtls_threading_mutex_t mbedtls_threading_gmtime_mutex;
 #endif /* !_POSIX_VERSION || 200112L > _POSIX_THREAD_SAFE_FUNCTIONS */
 #endif /* !_WIN32 && (unix || __unix || __unix__ ||
         * (__APPLE__ && __MACH__)) */
-#endif /* MBEDTLS_HAVE_TIME_DATE && !MBEDTLS_PLATFORM_GMTIME_ALT */
+#endif /* MBEDTLS_HAVE_TIME_DATE && !MBEDTLS_PLATFORM_GMTIME_R_ALT */
 #endif /* MBEDTLS_THREADING_C */
 
 #ifdef __cplusplus
diff --git a/library/platform_util.c b/library/platform_util.c
index c248cf529..8bd53c666 100644
--- a/library/platform_util.c
+++ b/library/platform_util.c
@@ -75,7 +75,7 @@ void mbedtls_platform_zeroize( void *buf, size_t len )
 }
 #endif /* MBEDTLS_PLATFORM_ZEROIZE_ALT */
 
-#if defined(MBEDTLS_HAVE_TIME_DATE) && !defined(MBEDTLS_PLATFORM_GMTIME_ALT)
+#if defined(MBEDTLS_HAVE_TIME_DATE) && !defined(MBEDTLS_PLATFORM_GMTIME_R_ALT)
 #include <time.h>
 #if !defined(_WIN32) && (defined(unix) || \
     defined(__unix) || defined(__unix__) || (defined(__APPLE__) && \
@@ -94,8 +94,8 @@ void mbedtls_platform_zeroize( void *buf, size_t len )
 #endif /* !_WIN32 && (unix || __unix || __unix__ ||
         * (__APPLE__ && __MACH__)) */
 
-struct tm *mbedtls_platform_gmtime( const mbedtls_time_t *tt,
-                                    struct tm *tm_buf )
+struct tm *mbedtls_platform_gmtime_r( const mbedtls_time_t *tt,
+                                      struct tm *tm_buf )
 {
 #if defined(_WIN32) && !defined(EFIX64) && !defined(EFI32)
     return( ( gmtime_s( tm_buf, tt ) == 0 ) ? tm_buf : NULL );
@@ -124,4 +124,4 @@ struct tm *mbedtls_platform_gmtime( const mbedtls_time_t *tt,
     return( ( lt == NULL ) ? NULL : tm_buf );
 #endif /* _WIN32 && !EFIX64 && !EFI32 */
 }
-#endif /* MBEDTLS_HAVE_TIME_DATE && MBEDTLS_PLATFORM_GMTIME_ALT */
+#endif /* MBEDTLS_HAVE_TIME_DATE && MBEDTLS_PLATFORM_GMTIME_R_ALT */
diff --git a/library/threading.c b/library/threading.c
index 1885efdfc..3abb17c0b 100644
--- a/library/threading.c
+++ b/library/threading.c
@@ -37,7 +37,7 @@
 
 #include "mbedtls/threading.h"
 
-#if defined(MBEDTLS_HAVE_TIME_DATE) && !defined(MBEDTLS_PLATFORM_GMTIME_ALT)
+#if defined(MBEDTLS_HAVE_TIME_DATE) && !defined(MBEDTLS_PLATFORM_GMTIME_R_ALT)
 #if !defined(_WIN32) && (defined(unix) || \
     defined(__unix) || defined(__unix__) || (defined(__APPLE__) && \
     defined(__MACH__)))
@@ -54,7 +54,7 @@
 #endif /* !_POSIX_VERSION || 200112L > _POSIX_THREAD_SAFE_FUNCTIONS */
 #endif /* !_WIN32 && (unix || __unix || __unix__ ||
         * (__APPLE__ && __MACH__)) */
-#endif /* MBEDTLS_HAVE_TIME_DATE && !MBEDTLS_PLATFORM_GMTIME_ALT */
+#endif /* MBEDTLS_HAVE_TIME_DATE && !MBEDTLS_PLATFORM_GMTIME_R_ALT */
 
 #if defined(MBEDTLS_THREADING_PTHREAD)
 static void threading_mutex_init_pthread( mbedtls_threading_mutex_t *mutex )
diff --git a/library/x509.c b/library/x509.c
index c17697b22..52b5b649f 100644
--- a/library/x509.c
+++ b/library/x509.c
@@ -898,7 +898,7 @@ static int x509_get_current_time( mbedtls_x509_time *now )
     int ret = 0;
 
     tt = mbedtls_time( NULL );
-    lt = mbedtls_platform_gmtime( &tt, &tm_buf );
+    lt = mbedtls_platform_gmtime_r( &tt, &tm_buf );
 
     if( lt == NULL )
         ret = -1;