diff --git a/clang-format-all b/clang-format-all
index 645c3ce..80826bf 100755
--- a/clang-format-all
+++ b/clang-format-all
@@ -21,6 +21,11 @@ function usage {
     exit 1
 }
 
+# There is no realpath command in MacOS, so we define it here
+realpath() {
+    [[ $1 = /* ]] && echo "$1" || echo "$PWD/${1#./}"
+}
+
 if [ $# -eq 0 ]; then
     usage
 fi