--- firefox-50.1.0.old/config/config.mk 2016-11-01 04:15:27.000000000 +0800
+++ firefox-50.1.0.new/config/config.mk 2017-01-01 20:40:17.313820042 +0800
@@ -556,7 +556,7 @@
 
 ifneq (,$(MOZ_LIBSTDCXX_TARGET_VERSION)$(MOZ_LIBSTDCXX_HOST_VERSION))
 CHECK_STDCXX = $(call CHECK_SYMBOLS,$(1),GLIBCXX,libstdc++,v[1] > 3 || (v[1] == 3 && v[2] == 4 && v[3] > 16))
-CHECK_GLIBC = $(call CHECK_SYMBOLS,$(1),GLIBC,libc,v[1] > 2 || (v[1] == 2 && v[2] > 12))
+CHECK_GLIBC = $(call CHECK_SYMBOLS,$(1),GLIBC,libc,v[1] > 2 || (v[1] == 2 && v[2] > 19))
 endif
 
 ifeq (,$(filter $(OS_TARGET),WINNT Darwin))