diff --git a/compiler/builtins/bitcode/run-tests.sh b/compiler/builtins/bitcode/run-tests.sh
index 4f5d27715e..2892ba1f74 100755
--- a/compiler/builtins/bitcode/run-tests.sh
+++ b/compiler/builtins/bitcode/run-tests.sh
@@ -4,3 +4,6 @@ set -euxo pipefail
 
 # Test every zig
 find src/*.zig -type f -print0 | xargs -n 1 -0 zig test --library c
+
+# fmt every zig
+find src/*.zig -type f -print0 | xargs -n 1 -0 zig fmt --check