diff --git a/ChangeLog b/ChangeLog
index 63e084a82..853e5578e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -22,6 +22,9 @@ Changes
    * Improve testing in configurations that omit certain hashes or
      public-key algorithms. Includes contributions by Gert van Dijk.
    * Improve negative testing of X.509 parsing.
+   * Do not define global mutexes around readdir() and gmtime() in
+     configurations where the feature is disabled. Found and fixed by Gergely
+     Budai.
 
 = mbed TLS 2.1.11 branch released 2018-03-16
 
diff --git a/include/mbedtls/threading.h b/include/mbedtls/threading.h
index c39cbf24d..3218f5cdf 100644
--- a/include/mbedtls/threading.h
+++ b/include/mbedtls/threading.h
@@ -81,6 +81,7 @@ void mbedtls_threading_set_alt( void (*mutex_init)( mbedtls_threading_mutex_t *
 void mbedtls_threading_free_alt( void );
 #endif /* MBEDTLS_THREADING_ALT */
 
+#if defined(MBEDTLS_THREADING_C)
 /*
  * The function pointers for mutex_init, mutex_free, mutex_ and mutex_unlock
  *
@@ -94,8 +95,13 @@ extern int (*mbedtls_mutex_unlock)( mbedtls_threading_mutex_t *mutex );
 /*
  * Global mutexes
  */
+#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 07586756f..f1c37245c 100644
--- a/library/threading.c
+++ b/library/threading.c
@@ -111,8 +111,12 @@ void mbedtls_threading_set_alt( void (*mutex_init)( mbedtls_threading_mutex_t *
     mbedtls_mutex_lock = mutex_lock;
     mbedtls_mutex_unlock = mutex_unlock;
 
+#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
 }
 
 /*
@@ -120,8 +124,12 @@ void mbedtls_threading_set_alt( void (*mutex_init)( mbedtls_threading_mutex_t *
  */
 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 */
 
@@ -131,7 +139,11 @@ void mbedtls_threading_free_alt( void )
 #ifndef MUTEX_INIT
 #define MUTEX_INIT
 #endif
+#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 */