diff --git a/.prettierignore b/.prettierignore
index 9f9b142..0ab4dc0 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -1,6 +1,7 @@
 /node_modules/
 /coverage/
 /.nyc_output/
+/testdata/
 
 # Don't fight npm i --save
 /package.json