diff --git a/rustfmt.toml b/rustfmt.toml
index 73f8cc1ff68..2a034845c6e 100644
--- a/rustfmt.toml
+++ b/rustfmt.toml
@@ -6,6 +6,8 @@ merge_derives = false
 # by default we ignore everything in the repository
 # tidy only checks files which are not ignored, each entry follows gitignore style
 ignore = [
+    "build",
+
     # tests for now are not formatted, as they are sometimes pretty-printing constrained
     # (and generally rustfmt can move around comments in UI-testing incompatible ways)
     "src/test",