-# flag checks are grouped together to speed the checks up a bit..
-CFLAGS += $(call cc-option,-Wall -Wshadow,)
+CFLAGS += $(call cc-option,-Wall,)
+CFLAGS += $(call cc-option,-Wshadow,)
+CFLAGS += $(call cc-option,-Wwrite-strings,)
+CFLAGS += $(call cc-option,-Wundef,)
+CFLAGS += $(call cc-option,-Wstrict-prototypes,)
+CFLAGS += $(call cc-option,-Wunused -Wunused-parameter,)
+CFLAGS += $(call cc-option,-Wunused-function -Wunused-value,)
+CFLAGS += $(call cc-option,-Wmissing-prototypes -Wmissing-declarations,)
+# warn about C99 declaration after statement
+CFLAGS += $(call cc-option,-Wdeclaration-after-statement,)
+# If you want to add more -Wsomething above, make sure that it is
+# still possible to build bbox without warnings.
+