diff --git a/include/mbedtls/threading.h b/include/mbedtls/threading.h
index b416d47..b0c34ec 100644
--- a/include/mbedtls/threading.h
+++ b/include/mbedtls/threading.h
@@ -97,7 +97,7 @@
  */
 extern mbedtls_threading_mutex_t mbedtls_threading_readdir_mutex;
 extern mbedtls_threading_mutex_t mbedtls_threading_gmtime_mutex;
-#endif
+#endif /* MBEDTLS_THREADING_C */
 
 #ifdef __cplusplus
 }