diff --git a/collects/unstable/gui/slideshow.rkt b/collects/unstable/gui/slideshow.rkt
index c4db59bf6a..55a5db5cca 100644
--- a/collects/unstable/gui/slideshow.rkt
+++ b/collects/unstable/gui/slideshow.rkt
@@ -1,7 +1,7 @@
 #lang racket
 
 (require slideshow/base slideshow/pict
-         racket/splicing racket/stxparam racket/gui/base
+         racket/splicing racket/stxparam racket/gui/base racket/block
          unstable/define)
 
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