diff --git a/@miSim/validate.m b/@miSim/validate.m
index 11dbcf6..03a4fff 100644
--- a/@miSim/validate.m
+++ b/@miSim/validate.m
@@ -15,12 +15,14 @@ function validate(obj)
     end
 
     %% Obstacle Validators
-    AO_collisions = cellfun(@(a) cellfun(@(o) o.contains(a.pos), obj.obstacles), obj.agents, "UniformOutput", false);
-    AO_collisions = vertcat(AO_collisions{:});
-    if any(AO_collisions)
-        [idx, idy] = find(AO_collisions);
-        for ii = 1:size(idx, 1)
-            error("Agent(s) %d colliding with obstacle(s) %d", idx(ii), idy(ii));
+    % Agent-Obstacle Collision Detection
+    for jj = 1:size(obj.obstacles, 1)
+        for kk = 1:size(obj.agents, 1)
+            P = min(max(obj.agents{kk}.pos, obj.obstacles{jj}.minCorner), obj.obstacles{jj}.maxCorner);
+            d = obj.agents{kk}.pos - P;
+            if dot(d, d) <= obj.agents{kk}.collisionGeometry.radius^2
+                error("%s colliding with %s", obj.agents{kk}.label, obj.obstacles{jj}.label); % this will cause quadprog to fail
+            end
         end
     end
 
diff --git a/test/parametricTestSuite.m b/test/parametricTestSuite.m
index 94c4dc4..eaa498a 100644
--- a/test/parametricTestSuite.m
+++ b/test/parametricTestSuite.m
@@ -178,9 +178,13 @@ classdef parametricTestSuite < matlab.unittest.TestCase
 
                         % Check if the obstacle collides with an agent
                         if ~retry
-                            AO_collisions = cellfun(@(a) cellfun(@(o) o.contains(a.pos), obstacles), agents, "UniformOutput", false);
-                            if any(vertcat(AO_collisions{:}))
-                                retry = true;
+                            for kk = 1:size(agents, 1)
+                                P = min(max(agents{kk}.pos, obstacles{jj}.minCorner), obstacles{jj}.maxCorner);
+                                d = agents{kk}.pos - P;
+                                if dot(d, d) <= agents{kk}.collisionGeometry.radius^2
+                                    retry = true;
+                                    break;
+                                end
                             end
                         end