diff --git a/classlib/src/main/java/org/teavm/classlib/java/util/TCollection.java b/classlib/src/main/java/org/teavm/classlib/java/util/TCollection.java
index c4600a3b0..0b6979c88 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/util/TCollection.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/util/TCollection.java
@@ -16,6 +16,7 @@
 package org.teavm.classlib.java.util;
 
 import java.util.Spliterator;
+import java.util.function.IntFunction;
 import java.util.function.Predicate;
 import org.teavm.classlib.java.lang.TIterable;
 import org.teavm.classlib.java.util.stream.TStream;
@@ -33,6 +34,10 @@ public interface TCollection<E> extends TIterable<E> {
 
     <T> T[] toArray(T[] a);
 
+    default <T> T[] toArray(IntFunction<T[]> gen) {
+        return toArray(gen.apply(0));
+    }
+
     boolean add(E e);
 
     boolean remove(Object o);