diff --git a/2001/ctk/.gitignore b/2001/ctk/.gitignore
index ca41c8f61..c050af53d 100644
--- a/2001/ctk/.gitignore
+++ b/2001/ctk/.gitignore
@@ -2,6 +2,7 @@
 # sort with: ../../bin/sgi
 *.dSYM
 ctk
+ctk.alt
 ctk.orig
 indent
 indent.c