diff --git a/include/SFML/System/Types.h b/include/SFML/System/Types.h
index 0848d19..97a4a41 100644
--- a/include/SFML/System/Types.h
+++ b/include/SFML/System/Types.h
@@ -27,5 +27,3 @@
 
 typedef struct sfBuffer sfBuffer;
 typedef struct sfClock sfClock;
-typedef struct sfMutex sfMutex;
-typedef struct sfThread sfThread;