diff --git a/.circleci/config.yml b/.circleci/config.yml
index 0c39dffb814a..4704c0295fc5 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -117,7 +117,6 @@ jobs:
 
    format:
      executor: ubuntu-build
-     resource_class: small
      steps:
        - run: rm -rf /home/circleci/project/.git # CircleCI git caching is likely broken
        - checkout
diff --git a/ci/do_ci.sh b/ci/do_ci.sh
index 82126ab2f22b..95722aa6b23b 100755
--- a/ci/do_ci.sh
+++ b/ci/do_ci.sh
@@ -277,16 +277,22 @@ elif [[ "$CI_TARGET" == "bazel.fuzzit_fuzzing" ]]; then
   ./ci/run_fuzzit.sh fuzzing
   exit 0
 elif [[ "$CI_TARGET" == "fix_format" ]]; then
+  # proto_format.sh needs to build protobuf.
+  setup_clang_toolchain
   echo "fix_format..."
   ./tools/check_format.py fix
   ./tools/format_python_tools.sh fix
+  ./tools/proto_format.sh fix
   exit 0
 elif [[ "$CI_TARGET" == "check_format" ]]; then
+  # proto_format.sh needs to build protobuf.
+  setup_clang_toolchain
   echo "check_format_test..."
   ./tools/check_format_test_helper.py --log=WARN
   echo "check_format..."
   ./tools/check_format.py check
   ./tools/format_python_tools.sh check
+  ./tools/proto_format.sh check
   exit 0
 elif [[ "$CI_TARGET" == "check_repositories" ]]; then
   echo "check_repositories..."
diff --git a/tools/proto_format.sh b/tools/proto_format.sh
index 71cfea2d0eb7..0271584e9e54 100755
--- a/tools/proto_format.sh
+++ b/tools/proto_format.sh
@@ -4,12 +4,6 @@
 
 set -e
 
-if [[ -n "$(git status --untracked-files=no --porcelain)" ]]
-then
-  echo "git status is dirty, $0 requires a clean git tree"
-  exit 1
-fi
-
 # TODO(htuch): This script started life by cloning docs/build.sh. It depends on
 # the @envoy_api//docs:protos target in a few places as a result. This is not
 # the precise set of protos we want to format, but as a starting place it seems
@@ -31,7 +25,13 @@ do
     declare PROTO_FILE_CANONICAL="${PROTO_FILE_WITHOUT_PREFIX/://}"
     declare DEST="api/${PROTO_FILE_CANONICAL}"
 
-    [[ -f "${DEST}" ]]
-    cp bazel-bin/external/envoy_api/"${PROTO_TARGET_CANONICAL}/${PROTO_FILE_CANONICAL}.proto" "${DEST}"
+    if [[ "$1" == "fix" ]]
+    then
+      [[ -f "${DEST}" ]]
+      cp bazel-bin/external/envoy_api/"${PROTO_TARGET_CANONICAL}/${PROTO_FILE_CANONICAL}.proto" "${DEST}"
+    else
+      diff bazel-bin/external/envoy_api/"${PROTO_TARGET_CANONICAL}/${PROTO_FILE_CANONICAL}.proto" "${DEST}" || \
+        (echo "$0 mismatch, either run ./ci/do_ci.sh fix_format or $0 fix to reformat."; exit 1)
+    fi
   done
 done