--- old/make/linux/makefiles/gcc.make	2015-09-16 15:17:16.000000000 -0700
+++ new/make/linux/makefiles/gcc.make	2015-09-16 15:17:16.000000000 -0700
@@ -205,6 +205,7 @@
   WARNINGS_ARE_ERRORS += -Wno-switch -Wno-tautological-constant-out-of-range-compare -Wno-tautological-compare
   WARNINGS_ARE_ERRORS += -Wno-delete-non-virtual-dtor -Wno-deprecated -Wno-format -Wno-dynamic-class-memaccess
   WARNINGS_ARE_ERRORS += -Wno-return-type -Wno-empty-body
+  WARNINGS_ARE_ERRORS += -Wno-undefined-bool-conversion
 endif
 
 WARNING_FLAGS = -Wpointer-arith -Wsign-compare -Wundef -Wunused-function -Wunused-value -Wformat=2 -Wreturn-type -Woverloaded-virtual