diff --git a/lib/hx509/Makefile.am b/lib/hx509/Makefile.am
index e32da3b93..470047758 100644
--- a/lib/hx509/Makefile.am
+++ b/lib/hx509/Makefile.am
@@ -11,7 +11,7 @@ BUILT_SOURCES =				\
 	hx509_err.c			\
 	hx509_err.h
 
-AM_YFLAGS = -d
+AM_YFLAGS = -o sel-gram.c
 
 dist_libhx509_la_SOURCES = \
 	ca.c \
diff --git a/lib/hx509/sel-gram.y b/lib/hx509/sel-gram.y
index 7e9d4f26d..0de0831bc 100644
--- a/lib/hx509/sel-gram.y
+++ b/lib/hx509/sel-gram.y
@@ -78,6 +78,10 @@
 %token <string> STRING
 %token <string> IDENTIFIER
 
+%precedence '!'
+%left kw_AND
+%left kw_OR
+
 %start start
 
 %%