--- /dev/null
+https://bugs.gentoo.org/673390
+
+--- a/sfbpf/Makefile.am
++++ b/sfbpf/Makefile.am
+@@ -43,13 +43,14 @@
+ libsfbpf_la_LDFLAGS = -version-info 0:1:0 @XCCFLAGS@
+
+ # use of $@ and $< here is a GNU idiom that borks BSD
+-sf_scanner.c: $(srcdir)/scanner.l
++sf_scanner.c: $(srcdir)/scanner.l tokdefs.h
+ @rm -f $(srcdir)/sf_scanner.c
+ $(srcdir)/runlex.sh $(V_LEX) -osf_scanner.c $(srcdir)/scanner.l
+
+ sf_scanner.o: sf_scanner.c tokdefs.h
+
+ tokdefs.h: sf_grammar.c
++
+ sf_grammar.c: $(srcdir)/grammar.y
+ @rm -f sf_grammar.c tokdefs.h
+ $(V_YACC) -d $(srcdir)/grammar.y