--- /dev/null
+diff --git a/js/src/moz.build b/js/src/moz.build
+index 1162cb70c..595ea9842 100644
+--- a/js/src/moz.build
++++ b/js/src/moz.build
+@@ -785,7 +785,7 @@ if CONFIG['JS_HAS_CTYPES']:
+ DEFINES['FFI_BUILDING'] = True
+
+ if CONFIG['GNU_CXX']:
+- CXXFLAGS += ['-Wno-shadow', '-Werror=format']
++ CXXFLAGS += ['-Wno-shadow']
+
+ # Suppress warnings in third-party code.
+ if CONFIG['CLANG_CXX']: