diff --git a/b2/Makefile b/b2/Makefile
index 8325655..119884b 100644
--- a/b2/Makefile
+++ b/b2/Makefile
@@ -11,7 +11,9 @@
 
 SHELL = /bin/bash
 
-CFLAGS = -g -Wall -Wextra -Wshadow $(shell pkg-config --cflags glib-2.0)
+CFLAGS = -g \
+	 -Wall -Wextra -Wshadow -Wmissing-prototypes -Wmissing-declarations \
+	 $(shell pkg-config --cflags glib-2.0)
 SLOPPY = -Wno-unused -Wno-implicit-function-declaration
 OBJS = bom.o boom.o chr.o comp.o db.o dump.o eval.o param.o relop.o \
        subex.o subst.o util.o \