diff --git a/.gitattributes b/.gitattributes
index cdfc2b2e..63a2b0dc 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -11,5 +11,6 @@
 *.dsk binary
 *.vhd binary
 *.crd binary
+*.dck binary
 sim_rev.h export-subst