diff --git a/tools/format-source.sh b/tools/format-source.sh
new file mode 100755
index 0000000..180e1ec
--- /dev/null
+++ b/tools/format-source.sh
@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+clang-format -i \
+  $(git ls-files '*.cpp' '*.cc' '*.cxx' '*.h' '*.hpp' '*.hh' '*.ipp')