diff --git a/docs/formatters-spec.md b/docs/formatters-spec.md
index ae2f7b2..0f2767d 100644
--- a/docs/formatters-spec.md
+++ b/docs/formatters-spec.md
@@ -34,7 +34,7 @@ $ rustfmt --edition 2018 src/main.rs src/lib.rs
 A formatted file MUST be valid. This is a strong contract; the syntax or
 semantic must never be broken by the formatter.
 
-A formatted file SHOULD be idempotent. Meaning that if the formatter it run
+A formatter SHOULD be idempotent. Meaning that if the formatter it run
 twice on a file, the file should not change on the second invocation.
 
 The formatter MUST NOT do file traversal when a list of files is passed to it.
diff --git a/treefmt.toml b/treefmt.toml
index 103fde8..aa40cba 100644
--- a/treefmt.toml
+++ b/treefmt.toml
@@ -28,7 +28,7 @@ excludes = ["examples/haskell/"]
 
 [formatter.nix]
 command = "nixpkgs-fmt"
-includes = ["*.nix"]
+includes = ["*.nix", ".foo.nix"]
 # Act as an example on how to exlude specific files
 excludes = ["examples/nix/sources.nix"]