diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 0d7967b..be29ccf 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -14,3 +14,10 @@ repos:
       - id: check-rebase
         args:
           - https://git.mfocko.xyz/mfocko/precommit-example.git
+-   repo: local
+    hooks:
+      - id: formatting
+        name: format source
+        entry: make format
+        language: system
+        pass_filenames: false
diff --git a/main.c b/main.c
index 5564806..3b7eca3 100644
--- a/main.c
+++ b/main.c
@@ -1,6 +1,4 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-int main() {
-    return NULL;
-}
+int main() { return NULL; }