diff --git a/collects/2htdp/private/world.ss b/collects/2htdp/private/world.ss
index 061ec0e117..c80468939f 100644
--- a/collects/2htdp/private/world.ss
+++ b/collects/2htdp/private/world.ss
@@ -181,7 +181,7 @@
                    (when live
                      (cond
                        [(and (<= 0 x width) (<= 0 y height)) (pmouse x y me)]
-                       [(memq me '(leave enter)) (pmouse x y me)]
+                       [(member me '("leave" "enter")) (pmouse x y me)]
                        [else (void)]))))
                (parent frame)
                (editor visible)
diff --git a/collects/2htdp/tests/mouse-evt.ss b/collects/2htdp/tests/mouse-evt.ss
new file mode 100644
index 0000000000..8e3740dc86
--- /dev/null
+++ b/collects/2htdp/tests/mouse-evt.ss
@@ -0,0 +1,45 @@
+#lang scheme
+
+(require 2htdp/universe)
+(require htdp/image)
+(require test-engine/scheme-tests)
+
+(define-struct posn (x y) #:transparent)
+
+(define world1 (make-posn 50 50))
+(define world-in (make-posn 100 100))
+(define world-out (make-posn 250 250))
+
+(define mt (empty-scene 500 500))
+(define sq (rectangle 10 10 'solid 'black))
+
+(define (draw a-world)
+  (cond
+    [(equal? a-world world1)
+     (place-image (text "move mouse in to canvas" 11 'red) 10 10
+       (place-image sq (posn-x a-world) (posn-y a-world) mt))]
+    [(equal? a-world world-in)
+     (place-image (text "move mouse out of canvas" 11 'red) 10 10
+       (place-image sq (posn-x a-world) (posn-y a-world) mt))]
+    [else
+      (place-image sq (posn-x a-world) (posn-y a-world) mt)]))
+
+(check-expect (mouse-handler 'w 100 100 "leave") (make-posn 250 250))
+
+(define (mouse-handler w x y me)
+ (cond
+   [(string=? "button-down" me) w]
+   [(string=? "button-up" me) w]
+   [(string=? "drag" me) w]
+   [(string=? "move" me) w]
+   [(string=? "enter" me) world-in]
+   [(string=? "leave" me) world-out]))
+
+(define (out? w) (equal? world-out w))
+
+(define (main w)
+  (big-bang world1 (on-draw draw) (stop-when out?) (on-mouse mouse-handler)))
+
+(test)
+
+(main 0)