diff --git a/core/.gitignore b/core/.gitignore
index 0ee3d5607c..be42d48852 100644
--- a/core/.gitignore
+++ b/core/.gitignore
@@ -5,3 +5,7 @@ node_modules
 # Ignore overrides of core's phpcs.xml.dist and phpunit.xml.dist.
 phpcs.xml
 phpunit.xml
+
+# Ignore package-lock.json that is automatically created when adding
+# dependencies by users of NPMv5.
+package-lock.json