diff --git a/collects/drscheme/private/language.ss b/collects/drscheme/private/language.ss
index 2d48d217bb..720116c057 100644
--- a/collects/drscheme/private/language.ss
+++ b/collects/drscheme/private/language.ss
@@ -344,6 +344,7 @@
                          [pretty-print-size-hook
                           (λ (value display? port)
                             (cond
+			      [(not (port-writes-special? port)) #f]
                               [(is-a? value snip%) 1]
                               [(use-number-snip? value) 1]
                               [(syntax? value) 1]