diff --git a/source-builder/defaults.mc b/source-builder/defaults.mc
index 67ba8cf..44fa838 100644
--- a/source-builder/defaults.mc
+++ b/source-builder/defaults.mc
@@ -141,7 +141,7 @@ __chmod:             exe,     required, '/bin/chmod'
 __chown:             exe,     required, '/usr/sbin/chown'
 __cp:                exe,     required, '/bin/cp'
 __cpp:               exe,     none,     '%{__cc} -E'
-__cvs:               exe,     required, '/usr/bin/cvs'
+__cvs:               exe,     optional, '/usr/bin/cvs'
 __cvs_z:             none,    none,     '%{__cvs} -z 9'
 __cxx:               exe,     required, '/usr/bin/g++'
 __flex:              exe,     required, '/usr/bin/flex'