diff --git a/prescheme/prescheme.scm b/prescheme/prescheme.scm
index 894f21f..8f90e84 100644
--- a/prescheme/prescheme.scm
+++ b/prescheme/prescheme.scm
@@ -13,6 +13,14 @@
   #:use-module (prescheme scheme48)
   #:use-module (prescheme platform)
   #:use-module (prescheme ps-defenum)
+  #:use-module ((ice-9 ports)
+                #:select (open-input-file
+                          open-output-file
+                          close-input-port
+                          close-output-port
+                          read-char
+                          peek-char)
+                #:prefix scheme:)
   #:export (shift-left arithmetic-shift-right logical-shift-right
 
             deallocate