diff --git a/package.json b/package.json
index d273ed5..8110963 100644
--- a/package.json
+++ b/package.json
@@ -29,7 +29,7 @@
     "eslint-plugin-standard": "^4.0.0",
     "mocha": "^6.0.0",
     "nyc": "^14.0.0",
-    "prettier": "^1.14.3",
+    "prettier": "~1.19.1",
     "proxyquire": "^2.1.0",
     "unexpected": "^11.0.0",
     "unexpected-documentation-site-generator": "^6.0.0",