1 files changed, 4 insertions, 2 deletions
diff --git a/rules.mk b/rules.mk
index eebc8b0..333e4f8 100644
--- a/rules.mk
+++ b/rules.mk
@@ -6,8 +6,10 @@ $(foreach V,$(filter %.SRCS, ${.VARIABLES}),\
 )
 
 # extra flags
-CFLAGS   += -isysteminclude -I../lib
-CXXFLAGS += -isysteminclude -I../lib -Drestrict=__restrict__
+CFLAGS   += -isysteminclude -I../lib \
+	    -Werror=implicit-function-declaration
+CXXFLAGS += -isysteminclude -I../lib -Drestrict=__restrict__ \
+	    -Werror=shadow
 
 # Suffix rules
 %.a: