diff --git a/library/threading.c b/library/threading.c
index e904b19..b499a44 100644
--- a/library/threading.c
+++ b/library/threading.c
@@ -112,6 +112,7 @@
     mbedtls_mutex_unlock = mutex_unlock;
 
     mbedtls_mutex_init( &mbedtls_threading_readdir_mutex );
+    mbedtls_mutex_init( &mbedtls_threading_gmtime_mutex );
 }
 
 /*
@@ -120,6 +121,7 @@
 void mbedtls_threading_free_alt( void )
 {
     mbedtls_mutex_free( &mbedtls_threading_readdir_mutex );
+    mbedtls_mutex_free( &mbedtls_threading_gmtime_mutex );
 }
 #endif /* MBEDTLS_THREADING_ALT */
 
@@ -130,5 +132,6 @@
 #define MUTEX_INIT
 #endif
 mbedtls_threading_mutex_t mbedtls_threading_readdir_mutex MUTEX_INIT;
+mbedtls_threading_mutex_t mbedtls_threading_gmtime_mutex MUTEX_INIT;
 
 #endif /* MBEDTLS_THREADING_C */