diff --git a/buildbot/master/files/config/environments.py b/buildbot/master/files/config/environments.py
index cda99bc0..41dc2901 100644
--- a/buildbot/master/files/config/environments.py
+++ b/buildbot/master/files/config/environments.py
@@ -112,8 +112,8 @@ def without(self, to_unset):
 # Use arm32 because it is the fastest cross builder.
 build_arm32 = build_arm.without(['SERVO_CACHE_DIR']) + Environment({
     'BUILD_TARGET': 'arm-unknown-linux-gnueabihf',
-    'CC': 'arm-linux-gnueabihf-gcc',
-    'CXX': 'arm-linux-gnueabihf-g++',
+    'CC_arm-unknown-linux-gnueabihf': 'arm-linux-gnueabihf-gcc',
+    'CXX_arm-unknown-linux-gnueabihf': 'arm-linux-gnueabihf-g++',
     'PATH': ':'.join([
         '{{ common.servo_home }}/bin',
         '/usr/local/sbin',
@@ -128,8 +128,8 @@ def without(self, to_unset):
 
 build_arm64 = build_arm + Environment({
     'BUILD_TARGET': 'aarch64-unknown-linux-gnu',
-    'CC': 'aarch64-linux-gnu-gcc',
-    'CXX': 'aarch64-linux-gnu-g++',
+    'CC_aarch64-unknown-linux-gnu': 'aarch64-linux-gnu-gcc',
+    'CXX_aarch64-unknown-linux-gnu': 'aarch64-linux-gnu-g++',
     'PATH': ':'.join([
         '{{ common.servo_home }}/bin',
         '/usr/local/sbin',