diff --git a/basis/windows/winsock/winsock.factor b/basis/windows/winsock/winsock.factor
index 7e6b2bd803..bd7304cde1 100755
--- a/basis/windows/winsock/winsock.factor
+++ b/basis/windows/winsock/winsock.factor
@@ -2,7 +2,7 @@
 ! See http://factorcode.org/license.txt for BSD license.
 USING: alien alien.c-types alien.strings alien.syntax arrays
 byte-arrays kernel math sequences windows.types windows.kernel32
-windows.errors math.bitwise io.encodings.utf16n ;
+windows.errors math.bitwise io.encodings.utf16n classes.struct ;
 IN: windows.winsock
 
 USE: libc