diff --git a/lib/util/LazySet.js b/lib/util/LazySet.js
index e973f903c3c..18b12f2f6cc 100644
--- a/lib/util/LazySet.js
+++ b/lib/util/LazySet.js
@@ -79,6 +79,8 @@ class LazySet {
 		} else {
 			this._toMerge.add(iterable);
 			this._needMerge = true;
+			// Avoid a memory leak
+			if (this._toMerge.size > 100000) this._merge();
 		}
 		return this;
 	}