diff --git a/support/xhpast/Makefile b/support/xhpast/Makefile
index 176ce72..e0e5380 100644
--- a/support/xhpast/Makefile
+++ b/support/xhpast/Makefile
@@ -1,70 +1,70 @@
-BISONFLAGS = --verbose -d
+BISONFLAGS = --verbose -d -Wall
 CPPFLAGS   = -fPIC -Wall
 FLEXFLAGS  = -C
 
 ifdef DEBUG
 	BISONFLAGS += --debug
 	CPPFLAGS   += -ggdb -DDEBUG
 	FLEXFLAGS  += --debug
 else
 	CPPFLAGS  += -O3 -minline-all-stringops
 endif
 
 ifdef PROFILE
 	CPPFLAGS += -pg
 endif
 
 ifdef STATIC
 	CPPFLAGS += -static
 endif
 
 ifdef MSYSTEM
 	CPPFLAGS += -static-libgcc -static-libstdc++
 endif
 
 ROOT = ../../src/parser/xhpast
 
 all: xhpast
 
 clean:
 	-rm xhpast parser.yacc.output libxhpast.a *.o 2>/dev/null
 
 cleanall: clean
 	-rm scanner.lex.cpp scanner.lex.hpp parser.yacc.cpp parser.yacc.hpp
 
 install: xhpast
 	cp xhpast $(ROOT)/bin/xhpast
 
 scanner: scanner.l
 	flex $(FLEXFLAGS) --header-file=scanner.lex.hpp --outfile=scanner.lex.cpp $<
 	echo '/* @gen''er''ated */' >> scanner.lex.cpp
 	echo '/* @gen''er''ated */' >> scanner.lex.hpp
 
 parser: parser.y
 	bison $(BISONFLAGS) --output=parser.yacc.cpp $<
 	echo '/* @gen''er''ated */' >> parser.yacc.cpp
 	echo '/* @gen''er''ated */' >> parser.yacc.hpp
 
 node_names.hpp: generate_nodes.php
 	php -f generate_nodes.php
 	cp parser_nodes.php $(ROOT)/
 
 %.o: %.cpp
 	$(CXX) -c $(CPPFLAGS) -o $@ $<
 
 needparserscanner:
 	 @([ -e parser.yacc.hpp ] && [ -e parser.yacc.cpp ] && \
 	   [ -e scanner.lex.hpp ] && [ -e scanner.lex.cpp ]) \
 		|| (echo "Run 'make parser scanner' first.'" && exit 1)
 
 parser.yacc.o: needparserscanner scanner.lex.hpp
 
 scanner.lex.o: needparserscanner parser.yacc.hpp node_names.hpp scanner.lex.hpp
 
 libxhpast.a: astnode.o scanner.lex.o parser.yacc.o
 	$(AR) -crs $@ $^
 
 xhpast: xhpast.cpp libxhpast.a
 	$(CXX) $(CPPFLAGS) -o $@ $^
 
 .PHONY: all clean