Use $^ instead of explicitely listing .c files in recipe.
@ -28,7 +28,7 @@ MANDIR := $(DESTDIR)$(MANDIR)
pstack : pstack.c
$(CC) $(CPPFLAGS) $(CFLAGS) -o pstack pstack.c $(LDFLAGS)
$(CC) $(CPPFLAGS) $(CFLAGS) -o pstack $^ $(LDFLAGS)
clean:
rm -f pstack