diff --git a/library/platform_util.c b/library/platform_util.c
index 3ba2aea..c8cd52d 100644
--- a/library/platform_util.c
+++ b/library/platform_util.c
@@ -115,7 +115,7 @@
 
 #if !( ( defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L ) ||     \
        ( defined(_POSIX_THREAD_SAFE_FUNCTIONS ) &&                     \
-         _POSIX_THREAD_SAFE_FUNCTIONS >= 20112L ) )
+         _POSIX_THREAD_SAFE_FUNCTIONS >= 200112L ) )
 /*
  * This is a convenience shorthand macro to avoid checking the long
  * preprocessor conditions above. Ideally, we could expose this macro in
@@ -129,7 +129,7 @@
 
 #endif /* !( ( defined(_POSIX_VERSION) && _POSIX_VERSION >= 200809L ) ||     \
              ( defined(_POSIX_THREAD_SAFE_FUNCTIONS ) &&                     \
-                _POSIX_THREAD_SAFE_FUNCTIONS >= 20112L ) ) */
+                _POSIX_THREAD_SAFE_FUNCTIONS >= 200112L ) ) */
 
 struct tm *mbedtls_platform_gmtime_r( const mbedtls_time_t *tt,
                                       struct tm *tm_buf )