--- a/browser/config/mozconfigs/win64/common-opt
+++ b/browser/config/mozconfigs/win64/common-opt
@@ -20,13 +20,10 @@ fi
 ac_add_options --with-google-oauth-api-keyfile=${_google_oauth_api_keyfile}
 ac_add_options --with-mozilla-api-keyfile=/c/builds/mozilla-desktop-geoloc-api.key
 
 # Needed to enable breakpad in application.ini
 export MOZILLA_OFFICIAL=1
 
 export MOZ_TELEMETRY_REPORTING=1
 
-# Treat warnings as errors in directories with FAIL_ON_WARNINGS.
-ac_add_options --enable-warnings-as-errors
-
 # Package js shell.
 export MOZ_PACKAGE_JSSHELL=1

--- a/browser/config/mozconfigs/win64/debug
+++ b/browser/config/mozconfigs/win64/debug
@@ -15,17 +15,14 @@ if [ -f /c/builds/google-oauth-api.key ]
 else
   _google_oauth_api_keyfile=/e/builds/google-oauth-api.key
 fi
 ac_add_options --with-google-oauth-api-keyfile=${_google_oauth_api_keyfile}
 
 # Needed to enable breakpad in application.ini
 export MOZILLA_OFFICIAL=1
 
-# Treat warnings as errors in directories with FAIL_ON_WARNINGS.
-ac_add_options --enable-warnings-as-errors
-
 # Package js shell.
 export MOZ_PACKAGE_JSSHELL=1
 
 . $topsrcdir/build/win64/mozconfig.vs2013
 
 . "$topsrcdir/build/mozconfig.common.override"