diff --git a/src/agent.rs b/src/agent.rs
index db15ccd..443ce16 100644
--- a/src/agent.rs
+++ b/src/agent.rs
@@ -103,6 +103,18 @@ fn random_move() -> Move {
     .into(),
   )
 }
+fn random_move_within(
+  (top, right, bottom, left): (Distance, Distance, Distance, Distance),
+) -> Move {
+  loop {
+    let mv = random_move();
+    if let Move::TryMove(Direction { x, y }) = mv {
+      if top + y > 0 && bottom - y > 0 && left + x > 0 && right - x > 0 {
+        return mv;
+      }
+    }
+  }
+}
 
 impl Agent for SimpleAgent {
   fn next_move(&self, view: WorldView) -> Move {
@@ -113,10 +125,10 @@ impl Agent for SimpleAgent {
         .find(|(dist, id)| dist.x.abs() <= 1 && dist.y.abs() <= 1 && Some(*id) != view.tagged_by)
       {
         Some((_, other)) => Move::TryTag(*other),
-        None => random_move(),
+        None => random_move_within(view.bounds_distance),
       }
     } else {
-      random_move()
+      random_move_within(view.bounds_distance)
     }
   }
 }
diff --git a/src/world.rs b/src/world.rs
index aeaf9cf..37969bc 100644
--- a/src/world.rs
+++ b/src/world.rs
@@ -78,13 +78,17 @@ impl ActualWorld {
           self.tagged_by = Some(id);
         }
         Move::TryMove(dir) => {
-          // FIXME check out of bounds
           // FIXME check speed
           let entry = self.agent_positions.entry(id);
+          let size = &self.size;
           assert!(matches!(entry, Entry::Occupied(_)));
           entry.and_modify(|e| {
             e.x += dir.x;
+            assert!(e.x > 0);
+            assert!(e.x < size.x);
             e.y += dir.y;
+            assert!(e.y > 0);
+            assert!(e.y < size.y);
           });
         }
       }
@@ -133,4 +137,17 @@ mod test {
     assert_eq!(world.tagged, 0);
     assert_eq!(world.tagged_by, Some(1));
   }
+
+  #[test]
+  #[should_panic]
+  fn move_out_of_bounds() {
+    let mut world = ActualWorld::new(
+      Position { x: 1, y: 1 },
+      vec![(
+        Position { x: 0, y: 0 },
+        Box::new(ScriptedAgent::new(vec![Move::TryMove((-1, -1).into())])),
+      )],
+    );
+    world.do_step();
+  }
 }