diff --git a/infra/bots/bot.py b/infra/bots/bot.py
index faacbf3..7bf597a 100644
--- a/infra/bots/bot.py
+++ b/infra/bots/bot.py
@@ -21,8 +21,9 @@
   mac_toolchain = os.path.join(os.getcwd(), sys.argv[3])
   xcode_app_path = os.path.join(os.getcwd(), sys.argv[4])
   # See mapping of Xcode version to Xcode build version here:
-  # https://chromium.googlesource.com/chromium/tools/build/+/master/scripts/slave/recipe_modules/ios/api.py#37
-  XCODE_BUILD_VERSION = '11c29'
+  # https://chrome-infra-packages.appspot.com/p/infra_internal/ios/xcode/mac/+/
+  XCODE_BUILD_VERSION = '12d4e'   # xcode 12.4
+  call('rm -rf {xcode_app_path}'.format(xcode_app_path=xcode_app_path))
   call(('{mac_toolchain}/mac_toolchain install '
         '-kind mac '
         '-xcode-version {xcode_build_version} '
diff --git a/infra/bots/tasks.json b/infra/bots/tasks.json
index 03f60a6..f2419d5 100644
--- a/infra/bots/tasks.json
+++ b/infra/bots/tasks.json
@@ -99,7 +99,7 @@
         "mac_toolchain",
         "cache/Xcode_skcms.app"
       ],
-      "dimensions": ["os:Mac-10.14.6", "gpu:none", "pool:Skia"],
+      "dimensions": ["os:Mac-10.15", "gpu:none", "pool:Skia"],
       "max_attempts": 1,
       "service_account": "skia-external-compile-tasks@skia-swarming-bots.iam.gserviceaccount.com"
     },
diff --git a/ninja/common b/ninja/common
index bff549f..2984f83 100644
--- a/ninja/common
+++ b/ninja/common
@@ -4,6 +4,8 @@
 # Each compiler has enabled all the warnings it can.
 # Here we make them errors, and disable a few we don't want bothering us.
 warnings = -Werror $
+           -Wno-unknown-warning-option $
+           -Wno-poison-system-directories $
            -Wno-double-promotion $
            -Wno-float-equal $
            -Wno-padded $