diff --git a/src/Cuboid.cpp b/src/Cuboid.cpp
index dc8df8500..2400c64f3 100644
--- a/src/Cuboid.cpp
+++ b/src/Cuboid.cpp
@@ -72,6 +72,9 @@ int cCuboid::GetVolume(void) const
 
 bool cCuboid::DoesIntersect(const cCuboid & a_Other) const
 {
+	ASSERT(IsSorted());
+	ASSERT(a_Other.IsSorted());
+	
 	// In order for cuboids to intersect, each of their coord intervals need to intersect
 	return (
 		DoIntervalsIntersect(p1.x, p2.x, a_Other.p1.x, a_Other.p2.x) &&
@@ -86,6 +89,9 @@ bool cCuboid::DoesIntersect(const cCuboid & a_Other) const
 
 bool cCuboid::IsCompletelyInside(const cCuboid & a_Outer) const
 {
+	ASSERT(IsSorted());
+	ASSERT(a_Outer.IsSorted());
+	
 	return (
 		(p1.x >= a_Outer.p1.x) &&
 		(p2.x <= a_Outer.p2.x) &&
diff --git a/src/Cuboid.h b/src/Cuboid.h
index 50a69b853..b95517f69 100644
--- a/src/Cuboid.h
+++ b/src/Cuboid.h
@@ -34,7 +34,8 @@ public:
 	Works on unsorted cuboids, too. */
 	int GetVolume(void) const;
 	
-	/** Returns true if the cuboids have at least one voxel in common. Both coords are considered inclusive. */
+	/** Returns true if the cuboids have at least one voxel in common. Both coords are considered inclusive.
+	Assumes both cuboids are sorted. */
 	bool DoesIntersect(const cCuboid & a_Other) const;
 
 	bool IsInside(const Vector3i & v)	const
@@ -64,7 +65,8 @@ public:
 		);
 	}
 	
-	/** Returns true if this cuboid is completely inside the specifie cuboid (in all 6 coords) */
+	/** Returns true if this cuboid is completely inside the specifie cuboid (in all 6 coords).
+	Assumes both cuboids are sorted. */
 	bool IsCompletelyInside(const cCuboid & a_Outer) const;
 	
 	/** Moves the cuboid by the specified offsets in each direction */
@@ -72,7 +74,7 @@ public:
 	
 	/** Expands the cuboid by the specified amount in each direction.
 	Works on unsorted cuboids as well.
-	Note that this function doesn't check for underflows. */
+	Note that this function doesn't check for underflows when using negative amounts. */
 	void Expand(int a_SubMinX, int a_AddMaxX, int a_SubMinY, int a_AddMaxY, int a_SubMinZ, int a_AddMaxZ);
 	
 	/** Clamps both X coords to the specified range. Works on unsorted cuboids, too. */