diff --git a/collects/picturing-programs/tests/tiles-error-tests.rkt b/collects/picturing-programs/tests/tiles-error-tests.rkt
index f5f98274ac..a488f15014 100644
--- a/collects/picturing-programs/tests/tiles-error-tests.rkt
+++ b/collects/picturing-programs/tests/tiles-error-tests.rkt
@@ -4,34 +4,34 @@
 (require picturing-programs)
 
 (check-error (reflect-horiz 17)
-             "reflect-horiz: expected <image> as first argument, given: 17")
+             "reflect-horiz: expected <image> as first argument, given 17")
 (check-error (reflect-vert "hello")
-             "reflect-vert: expected <image> as first argument, given: \"hello\"")
+             "reflect-vert: expected <image> as first argument, given \"hello\"")
 (check-error (reflect-main-diag true)
-             "reflect-main-diag: expected <image> as first argument, given: true")
+             "reflect-main-diag: expected <image> as first argument, given true")
 (check-error (reflect-other-diag false)
-             "reflect-other-diag: expected <image> as first argument, given: false")
+             "reflect-other-diag: expected <image> as first argument, given false")
 (check-error (flip-main 'blue)
-             "flip-main: expected <image> as first argument, given: 'blue")
+             "flip-main: expected <image> as first argument, given 'blue")
 (check-error (flip-other "snark")
-             "flip-other: expected <image> as first argument, given: \"snark\"")
+             "flip-other: expected <image> as first argument, given \"snark\"")
 (check-error (crop-left pic:hacker 50)
-             "crop-left: expected <natural number <= 48> as second argument, given: 50")
+             "crop-left: expected <natural number <= 48> as second argument, given 50")
 (check-error (crop-right pic:bloch 100)
-             "crop-right: expected <natural number <= 93> as second argument, given: 100")
+             "crop-right: expected <natural number <= 93> as second argument, given 100")
 (check-error (crop-top pic:book 56)
-             "crop-top: expected <natural number <= 39> as second argument, given: 56")
+             "crop-top: expected <natural number <= 39> as second argument, given 56")
 (check-error (crop-bottom pic:hacker 56)
-             "crop-bottom: expected <natural number <= 48> as second argument, given: 56")
+             "crop-bottom: expected <natural number <= 48> as second argument, given 56")
 (check-error (crop-left pic:hacker -3)
-             "crop-left: expected <natural number <= 48> as second argument, given: -3")
+             "crop-left: expected <natural number <= 48> as second argument, given -3")
 (check-error (crop-top pic:book 3.2)
-             "crop-top: expected <natural number <= 39> as second argument, given: 3.2")
+             "crop-top: expected <natural number <= 39> as second argument, given 3.2")
 (check-error (crop-bottom pic:book pic:book)
-             "crop-bottom: expected <natural number <= 39> as second argument, given: #<image>")
+             "crop-bottom: expected <natural number <= 39> as second argument, given #<image>")
 (check-error (rotate-cw 17)
-             "rotate-cw: expected <image> as first argument, given: 17")
+             "rotate-cw: expected <image> as first argument, given 17")
 (check-error (rotate-ccw true)
-             "rotate-ccw: expected <image> as first argument, given: true")
+             "rotate-ccw: expected <image> as first argument, given true")
 (check-error (rotate-180 "goodbye")
-             "rotate-180: expected <image> as first argument, given: \"goodbye\"")
+             "rotate-180: expected <image> as first argument, given \"goodbye\"")