diff --git a/.github/workflows/main.yaml b/.github/workflows/main.yaml
new file mode 100644
index 0000000..3076dbf
--- /dev/null
+++ b/.github/workflows/main.yaml
@@ -0,0 +1,12 @@
+# CI workflow
+name: sledge
+on: [push, pull_request]
+
+# job control
+jobs:
+  format:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Clang Format
+        run: ./format.sh -d
diff --git a/format.sh b/format.sh
index 8c6a804..b901144 100755
--- a/format.sh
+++ b/format.sh
@@ -25,9 +25,34 @@ if ((major < required_major)) || ((minor < required_minor)) || ((patch < require
   exit 1
 fi
 
-# Match all *.c and *.h files in ./runtime
-# Excluding those in the jsmn or http-parser submodules
-# And format them with clang-format
-find ./runtime -type f -path "./*.[ch]" |
-  grep --invert-match -E "./runtime/thirdparty/*|./runtime/tests/gocr/*|./runtime/tests/TinyEKF/*|./runtime/tests/CMSIS_5_NN/*|./runtime/tests/sod/*|**/thirdparty/*" |
-  xargs clang-format -i
+help() {
+  echo "Usage: $0 [OPTION]..."
+  echo "Formats source code in the repository, applying formatting in place by default"
+  echo ""
+  echo "-h, --help        Print Help"
+  echo "-d, --dry-run     Dry run formatters, returning 0 when code passes, 1 otherwise"
+  echo ""
+  echo "Exit status:"
+  echo "0 if code required no formatting"
+  echo "non-zero exit status otherwise"
+}
+
+dry_run() {
+  find runtime \
+    \( -path "runtime/thirdparty" -o -path "runtime/tests/gocr" -o -path "runtime/tests/TinyEKF" -o -path "runtime/tests/CMSIS_5_NN" -o -path "runtime/tests/sod" -o -path "runtime/tests/**/thirdparty" \) -prune -false -o \
+    -type f \( -iname \*.h -o -iname \*.c -o -iname \*.s \) -print |
+    xargs clang-format -Werror -n -ferror-limit=0
+}
+
+format() {
+  find runtime \
+    \( -path "runtime/thirdparty" -o -path "runtime/tests/gocr" -o -path "runtime/tests/TinyEKF" -o -path "runtime/tests/CMSIS_5_NN" -o -path "runtime/tests/sod" -o -path "runtime/tests/**/thirdparty" \) -prune -false -o \
+    -type f \( -iname \*.h -o -iname \*.c -o -iname \*.s \) -print |
+    xargs clang-format -i
+}
+
+case $1 in
+  "-h" | "--help") help ;;
+  "-d" | "--dry-run") dry_run ;;
+  "") format ;;
+esac