diff --git a/src/ExpToCasExe/EXTERNLIB b/src/ExpToCasExe/EXTERNLIB
index 9a5a7e59c4..9f6ca33640 100644
--- a/src/ExpToCasExe/EXTERNLIB
+++ b/src/ExpToCasExe/EXTERNLIB
@@ -1,2 +1,3 @@
 TKernel
 TKExpress
+CSF_wsock32