diff --git a/Bonk/BroadPhase/SpatialHash.cs b/Bonk/BroadPhase/SpatialHash.cs
index f87b53f..9e5b953 100644
--- a/Bonk/BroadPhase/SpatialHash.cs
+++ b/Bonk/BroadPhase/SpatialHash.cs
@@ -31,8 +31,10 @@ namespace MoonTools.Core.Bonk
         /// <param name="id">A unique ID for the shape-transform pair.</param>
         /// <param name="shape"></param>
         /// <param name="transform2D"></param>
-        public void Insert<TShape2D>(T id, TShape2D shape, Transform2D transform2D) where TShape2D : struct, IShape2D
+        public void Insert(T id, IShape2D shape, Transform2D transform2D)
         {
+            if (shape == null) { throw new ArgumentNullException(nameof(shape)); }
+
             var box = shape.AABB(transform2D);
             var minHash = Hash(box.MinX, box.MinY);
             var maxHash = Hash(box.MaxX, box.MaxY);
@@ -60,9 +62,11 @@ namespace MoonTools.Core.Bonk
         /// <summary>
         /// Retrieves all the potential collisions of a shape-transform pair. Excludes any shape-transforms with the given ID.
         /// </summary>
-        public IEnumerable<(T, IShape2D, Transform2D)> Retrieve<TShape2D>(T id, TShape2D shape, Transform2D transform2D) where TShape2D : struct, IShape2D
+        public IEnumerable<(T, IShape2D, Transform2D)> Retrieve(T id, IShape2D shape, Transform2D transform2D)
         {
-            var box = shape.AABB(transform2D);
+            if (shape == null) { throw new ArgumentNullException(paramName: nameof(shape)); }
+
+            AABB box = shape.AABB(transform2D);
             var minHash = Hash(box.MinX, box.MinY);
             var maxHash = Hash(box.MaxX, box.MaxY);
 
diff --git a/Bonk/NarrowPhase/EPA2D.cs b/Bonk/NarrowPhase/EPA2D.cs
index 5bb5715..5860d2f 100644
--- a/Bonk/NarrowPhase/EPA2D.cs
+++ b/Bonk/NarrowPhase/EPA2D.cs
@@ -24,8 +24,11 @@ namespace MoonTools.Core.Bonk
         /// Returns a minimum separating vector in the direction from A to B.
         /// </summary>
         /// <param name="simplex">A simplex returned by the GJK algorithm.</param>
-        public static Vector2 Intersect<TShapeA, TShapeB>(TShapeA shapeA, Transform2D Transform2DA, TShapeB shapeB, Transform2D Transform2DB, Simplex2D simplex) where TShapeA : struct, IShape2D where TShapeB : struct, IShape2D
+        public static Vector2 Intersect(IShape2D shapeA, Transform2D Transform2DA, IShape2D shapeB, Transform2D Transform2DB, Simplex2D simplex)
         {
+            if (shapeA == null) { throw new ArgumentNullException(nameof(shapeA)); }
+            if (shapeB == null) { throw new ArgumentNullException(nameof(shapeB)); }
+
             var simplexVertices = simplex.Vertices.Select(vertex => vertex.ToVector2()).ToImmutableArray();
 
             var e0 = (simplexVertices[1].X - simplexVertices[0].X) * (simplexVertices[1].Y + simplexVertices[0].Y);