diff --git a/mp/src/public/vphysics/collision_set.h b/mp/src/public/vphysics/collision_set.h
index 66aaeb833..ac706eb68 100644
--- a/mp/src/public/vphysics/collision_set.h
+++ b/mp/src/public/vphysics/collision_set.h
@@ -8,6 +8,13 @@
 
 // A set of collision rules
 // NOTE: Defaults to all indices disabled
+
+#ifndef COLLISION_SET_H
+#define COLLISION_SET_H
+#ifdef _WIN32
+#pragma once
+#endif
+
 class IPhysicsCollisionSet
 {
 public:
@@ -17,4 +24,6 @@ public:
 	virtual void DisableCollisions( int index0, int index1 ) = 0;
 
 	virtual bool ShouldCollide( int index0, int index1 ) = 0;
-};
\ No newline at end of file
+};
+
+#endif  // COLLISION_SET_H
\ No newline at end of file
diff --git a/sp/src/public/vphysics/collision_set.h b/sp/src/public/vphysics/collision_set.h
index 66aaeb833..ac706eb68 100644
--- a/sp/src/public/vphysics/collision_set.h
+++ b/sp/src/public/vphysics/collision_set.h
@@ -8,6 +8,13 @@
 
 // A set of collision rules
 // NOTE: Defaults to all indices disabled
+
+#ifndef COLLISION_SET_H
+#define COLLISION_SET_H
+#ifdef _WIN32
+#pragma once
+#endif
+
 class IPhysicsCollisionSet
 {
 public:
@@ -17,4 +24,6 @@ public:
 	virtual void DisableCollisions( int index0, int index1 ) = 0;
 
 	virtual bool ShouldCollide( int index0, int index1 ) = 0;
-};
\ No newline at end of file
+};
+
+#endif  // COLLISION_SET_H
\ No newline at end of file