--- a/browser/config/mozconfigs/linux64/beta
+++ b/browser/config/mozconfigs/linux64/beta
@@ -6,9 +6,10 @@ fi
 
 . "$topsrcdir/browser/config/mozconfigs/linux64/common-opt"
 
 ac_add_options --enable-official-branding
 ac_add_options --enable-verify-mar
 
 mk_add_options MOZ_PGO=1
 
+. "$topsrcdir/build/unix/mozconfig.rust"
 . "$topsrcdir/build/mozconfig.common.override"

--- a/browser/config/mozconfigs/linux64/release
+++ b/browser/config/mozconfigs/linux64/release
@@ -13,9 +13,10 @@ ac_add_options --enable-official-brandin
 ac_add_options --enable-verify-mar
 
 mk_add_options MOZ_PGO=1
 
 # safeguard against someone forgetting to re-set EARLY_BETA_OR_EARLIER in
 # defines.sh during the beta cycle
 export BUILDING_RELEASE=1
 
+. "$topsrcdir/build/unix/mozconfig.rust"
 . "$topsrcdir/build/mozconfig.common.override"

--- a/browser/config/mozconfigs/macosx-universal/beta
+++ b/browser/config/mozconfigs/macosx-universal/beta
@@ -5,10 +5,11 @@ if [ -n "$ENABLE_RELEASE_PROMOTION" ]; t
   MOZ_AUTOMATION_UPDATE_PACKAGING=1
 fi
 
 . "$topsrcdir/browser/config/mozconfigs/macosx-universal/common-opt"
 
 ac_add_options --enable-official-branding
 ac_add_options --enable-verify-mar
 
+. "$topsrcdir/build/macosx/mozconfig.rust"
 . "$topsrcdir/build/mozconfig.common.override"
 . "$topsrcdir/build/mozconfig.cache"

--- a/browser/config/mozconfigs/macosx-universal/release
+++ b/browser/config/mozconfigs/macosx-universal/release
@@ -11,10 +11,11 @@ fi
 
 ac_add_options --enable-official-branding
 ac_add_options --enable-verify-mar
 
 # safeguard against someone forgetting to re-set EARLY_BETA_OR_EARLIER in
 # defines.sh during the beta cycle
 export BUILDING_RELEASE=1
 
+. "$topsrcdir/build/macosx/mozconfig.rust"
 . "$topsrcdir/build/mozconfig.common.override"
 . "$topsrcdir/build/mozconfig.cache"

--- a/browser/config/mozconfigs/whitelist
+++ b/browser/config/mozconfigs/whitelist
@@ -35,30 +35,28 @@ whitelist['nightly']['linux32'] += [
 
 whitelist['nightly']['linux64'] += [
     'export MOZILLA_OFFICIAL=1',
     'export MOZ_TELEMETRY_REPORTING=1',
     "mk_add_options PROFILE_GEN_SCRIPT='$(PYTHON) @MOZ_OBJDIR@/_profile/pgo/profileserver.py 10'",
     'STRIP_FLAGS="--strip-debug"',
     'ac_add_options --with-ccache=/usr/bin/ccache',
     '. "$topsrcdir/build/mozconfig.cache"',
-    '. "$topsrcdir/build/mozconfig.rust"',
 ]
 
 whitelist['nightly']['macosx-universal'] += [
     'if test "${MOZ_UPDATE_CHANNEL}" = "nightly"; then',
     'ac_add_options --with-macbundlename-prefix=Firefox',
     'fi',
     'mk_add_options MOZ_MAKE_FLAGS="-j12"',
     'ac_add_options --with-ccache',
     '. "$topsrcdir/build/mozconfig.cache"',
     'ac_add_options --disable-install-strip',
     'ac_add_options --enable-instruments',
     'ac_add_options --enable-dtrace',
-    '. "$topsrcdir/build/macosx/mozconfig.rust"',
 ]
 
 whitelist['nightly']['win32'] += [
     '. $topsrcdir/configs/mozilla2/win32/include/choose-make-flags',
     'mk_add_options MOZ_MAKE_FLAGS=-j1',
     '. "$topsrcdir/build/mozconfig.cache"',
     'if test "$IS_NIGHTLY" != ""; then',
     'ac_add_options --disable-auto-deps',