2 files changed, 3 insertions, 2 deletions
diff --git a/mk/cc.mk b/mk/cc.mk
index fcf05351..ffbf93a6 100644
--- a/mk/cc.mk
+++ b/mk/cc.mk
@@ -14,7 +14,8 @@ _CCFLAGS=	-pedantic -Wall -Wunused -Wimplicit -Wshadow -Wformat=2 \
 		-Wmissing-declarations -Wno-missing-prototypes -Wwrite-strings \
 		-Wbad-function-cast -Wnested-externs -Wcomment -Winline \
 		-Wchar-subscripts -Wcast-align -Wno-format-nonliteral \
-		-Wdeclaration-after-statement -Wsequence-point -Wextra
+		-Wdeclaration-after-statement -Wsequence-point -Wextra \
+		-fno-common
 _CC_FLAGS_SH=	if ! test -d .git; then echo ""; else for f in ${_CCFLAGS}; do \
 		if ${CC} $$f -S -o /dev/null -xc /dev/null >/dev/null 2>&1; \
 		then printf "%s" "$$f "; fi \
diff --git a/net.h b/net.h
index 1447aba0..363cb2a8 100644
--- a/net.h
+++ b/net.h
@@ -156,7 +156,7 @@ int if_route(const struct interface *,
 void free_routes(struct rt *);
 
 int open_udp_socket(struct interface *);
-const size_t udp_dhcp_len;
+extern const size_t udp_dhcp_len;
 ssize_t make_udp_packet(uint8_t **, const uint8_t *, size_t,
 			struct in_addr, struct in_addr);
 ssize_t get_udp_data(const uint8_t **, const uint8_t *);