--- a/makefile	2013-02-06 10:26:36.452829647 -0700
+++ b/makefile	2013-02-07 09:12:13.293898947 -0700
@@ -44,7 +44,7 @@
 LISTING = awk.h proto.h awkgram.y lex.c b.c main.c maketab.c parse.c \
 	lib.c run.c tran.c 
 
-SHIP = README FIXES $(SOURCE) ytab[ch].bak makefile  \
+SHIP = README FIXES $(SOURCE) makefile  \
 	 awk.1
 
 a.out:	ytab.o $(OFILES)
@@ -52,11 +52,15 @@
 
 $(OFILES):	awk.h ytab.h proto.h
 
-ytab.o:	awk.h proto.h awkgram.y
+#Clear dependency for parallel build: (make -j)
+#YACC generated y.tab.c and y.tab.h at the same time
+#this needs to be a static pattern rules otherwise multiple target
+#are mapped onto multiple executions of yacc, which overwrite 
+#each others outputs.
+y%.c y%.h:	awk.h proto.h awkgram.y
 	$(YACC) $(YFLAGS) awkgram.y
-	mv y.tab.c ytab.c
-	mv y.tab.h ytab.h
-	$(CC) $(CFLAGS) -c ytab.c
+	mv y.$*.c y$*.c
+	mv y.$*.h y$*.h
 
 proctab.c:	maketab
 	./maketab >proctab.c
@@ -64,23 +68,23 @@
 maketab:	ytab.h maketab.c
 	$(CC) $(CFLAGS) maketab.c -o maketab
 
-bundle:
+bundle: $(SHIP)
 	@cp ytab.h ytabh.bak
 	@cp ytab.c ytabc.bak
-	@bundle $(SHIP)
+	@bundle $(SHIP) ytabh.bak ytabc.bak
 
-tar:
+tar: $(SHIP)
 	@cp ytab.h ytabh.bak
 	@cp ytab.c ytabc.bak
 	@bundle $(SHIP) >awk.shar
-	@tar cf awk.tar $(SHIP)
+	@tar cf awk.tar $(SHIP) ytabh.bak ytabc.bak
 	gzip awk.tar
 	ls -l awk.tar.gz
-	@zip awk.zip $(SHIP)
+	@zip awk.zip $(SHIP) ytabh.bak ytabc.bak
 	ls -l awk.zip
 
 names:
 	@echo $(LISTING)
 
 clean:
-	rm -f a.out *.o *.obj maketab maketab.exe *.bb *.bbg *.da *.gcov *.gcno *.gcda # proctab.c
+	rm -f a.out *.o *.obj maketab maketab.exe *.bb *.bbg *.da *.gcov *.gcno *.gcda ytab.c ytab.h # proctab.c