diff --git a/src/collision/OverlappingPair.h b/src/collision/OverlappingPair.h
index cf2ccf25..4e657a0c 100644
--- a/src/collision/OverlappingPair.h
+++ b/src/collision/OverlappingPair.h
@@ -26,7 +26,7 @@
 #define	OVERLAPPING_PAIR_H
 
 // Libraries
-#include "../engine/PersistentContactCache.h"
+#include "PersistentContactCache.h"
 
 // ReactPhysics3D namespace
 namespace reactphysics3d {
diff --git a/src/engine/PersistentContactCache.cpp b/src/collision/PersistentContactCache.cpp
similarity index 100%
rename from src/engine/PersistentContactCache.cpp
rename to src/collision/PersistentContactCache.cpp
diff --git a/src/engine/PersistentContactCache.h b/src/collision/PersistentContactCache.h
similarity index 99%
rename from src/engine/PersistentContactCache.h
rename to src/collision/PersistentContactCache.h
index f62bede0..4e3bad16 100644
--- a/src/engine/PersistentContactCache.h
+++ b/src/collision/PersistentContactCache.h
@@ -36,7 +36,6 @@ namespace reactphysics3d {
 // Constants
 const uint MAX_CONTACTS_IN_CACHE = 4;           // Maximum number of contacts in the persistent cache
 
-// TODO : Move this class in collision/ folder
 
 /*  -------------------------------------------------------------------
     Class PersistentContactCache :