diff --git a/sys/unix/Makefile.top b/sys/unix/Makefile.top
index a0824a155..53fc5dbaf 100644
--- a/sys/unix/Makefile.top
+++ b/sys/unix/Makefile.top
@@ -1,5 +1,5 @@
 #      NetHack Top-level Makefile.
-# NetHack 3.7  Makefile.top    $NHDT-Date: 1597031649 2020/08/10 03:54:09 $  $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.52 $
+# NetHack 3.7  Makefile.top    $NHDT-Date: 1607810996 2020/12/12 22:09:56 $  $NHDT-Branch: NetHack-3.7 $:$NHDT-Revision: 1.63 $
 # Copyright (c) 2015 by Kenneth Lorber, Kensington, Maryland
 # NetHack may be freely redistributed.  See license for details.
 
@@ -320,7 +320,7 @@ clean:
 	( cd util ; $(MAKE) clean )
 	( cd dat ; $(MAKE) clean )
 	( cd doc ; $(MAKE) clean )
-	( cd lib/lua-$(LUA_VERSION)/src && $(MAKE) clean )
+	-( cd lib/lua-$(LUA_VERSION)/src && $(MAKE) clean )
 
 # 'make spotless' returns the source tree to near-distribution condition.
 # it removes .o files, executables, and compiled data files