diff --git a/browser/config/mozconfigs/win64/debug b/browser/config/mozconfigs/win64/debug
index b21ee05f408..1bbca84e73b 100644
--- a/browser/config/mozconfigs/win64/debug
+++ b/browser/config/mozconfigs/win64/debug
@@ -13,9 +13,6 @@ if test -z "${_PYMAKE}"; then
   mk_add_options MOZ_MAKE_FLAGS=-j1
 fi
 
-# 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
 
diff --git a/browser/config/mozconfigs/win64/nightly b/browser/config/mozconfigs/win64/nightly
index d3adcb087f6..1cb7f4be557 100644
--- a/browser/config/mozconfigs/win64/nightly
+++ b/browser/config/mozconfigs/win64/nightly
@@ -22,9 +22,6 @@ if test -z "${_PYMAKE}"; then
   mk_add_options MOZ_MAKE_FLAGS=-j1
 fi
 
-# 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