diff --git a/collects/mzlib/private/sigutil.ss b/collects/mzlib/private/sigutil.ss
index 26ce028..4dab29c 100644
--- a/collects/mzlib/private/sigutil.ss
+++ b/collects/mzlib/private/sigutil.ss
@@ -5,7 +5,6 @@
   (require (lib "stx.ss" "syntax"))
 
   (require "sigmatch.ss")
-  (require "../exstruct.ss")
   (require "../unit.ss")
   (require "../list.ss")
 
diff --git a/collects/mzlib/unitsig.ss b/collects/mzlib/unitsig.ss
index db3f06b..c071b5e 100644
--- a/collects/mzlib/unitsig.ss
+++ b/collects/mzlib/unitsig.ss
@@ -1,6 +1,5 @@
 
 (module unitsig mzscheme
-  (require "exstruct.ss")
   (require "unit.ss")
   (require "private/sigmatch.ss")