diff --git a/build.gradle b/build.gradle
index a959130..c821280 100644
--- a/build.gradle
+++ b/build.gradle
@@ -6,7 +6,7 @@ plugins {
 
 subprojects {
     group = 'dev.tommyjs'
-    version = '2.5.2'
+    version = '2.5.3'
 
     apply plugin: 'java-library'
     apply plugin: 'com.github.johnrengelman.shadow'
diff --git a/futur-api/src/main/java/dev/tommyjs/futur/util/ConcurrentResultArray.java b/futur-api/src/main/java/dev/tommyjs/futur/util/ConcurrentResultArray.java
index ec202f1..a59e9ae 100644
--- a/futur-api/src/main/java/dev/tommyjs/futur/util/ConcurrentResultArray.java
+++ b/futur-api/src/main/java/dev/tommyjs/futur/util/ConcurrentResultArray.java
@@ -1,35 +1,58 @@
 package dev.tommyjs.futur.util;
 
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.Arrays;
 import java.util.List;
-import java.util.concurrent.atomic.AtomicReference;
+import java.util.Objects;
+import java.util.concurrent.atomic.AtomicInteger;
 
 public class ConcurrentResultArray<T> {
 
-    private static final float RESIZE_FACTOR = 1.2F;
-
-    private final AtomicReference<T[]> ref;
+    private final T[] expected;
+    private final AtomicInteger size;
+    private T @Nullable [] unexpected;
 
     public ConcurrentResultArray(int expectedSize) {
         //noinspection unchecked
-        this.ref = new AtomicReference<>((T[]) new Object[expectedSize]);
+        this.expected = (T[]) new Object[expectedSize];
+        this.size = new AtomicInteger(0);
     }
 
     public void set(int index, T element) {
-        ref.updateAndGet(array -> {
-            if (array.length <= index) {
-                array = Arrays.copyOf(array, (int) (array.length * RESIZE_FACTOR));
+        size.updateAndGet(v -> Math.max(v, index + 1));
+        if (index < expected.length) {
+            expected[index] = element;
+            return;
+        }
+
+        int altIndex = index - expected.length;
+        synchronized (this) {
+            if (unexpected == null) {
+                //noinspection unchecked
+                unexpected = (T[]) new Object[Math.max(10, altIndex + 1)];
+            } else if (altIndex >= unexpected.length) {
+                int minGrowth = altIndex - unexpected.length + 1;
+                int prefGrowth = Math.max(1, unexpected.length >> 1);
+                int newLength = unexpected.length + Math.max(minGrowth, prefGrowth);
+                unexpected = Arrays.copyOf(unexpected, newLength);
             }
 
-            array[index] = element;
-            return array;
-        });
+            unexpected[altIndex] = element;
+        }
     }
 
     public @NotNull List<T> toList() {
-        return Arrays.asList(ref.get());
+        int size = this.size.get();
+        T[] result = Arrays.copyOf(expected, size);
+        if (size <= expected.length) {
+            return Arrays.asList(result);
+        }
+
+        System.arraycopy(Objects.requireNonNull(unexpected), 0,
+            result, expected.length, size - expected.length);
+        return Arrays.asList(result);
     }
 
 }
diff --git a/futur-api/src/test/java/dev/tommyjs/futur/PromiseTests.java b/futur-api/src/test/java/dev/tommyjs/futur/PromiseTests.java
index 7d89a17..cbe1983 100644
--- a/futur-api/src/test/java/dev/tommyjs/futur/PromiseTests.java
+++ b/futur-api/src/test/java/dev/tommyjs/futur/PromiseTests.java
@@ -8,11 +8,14 @@ import org.junit.jupiter.api.Test;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.*;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicReference;
+import java.util.stream.IntStream;
 import java.util.stream.Stream;
 
 public final class PromiseTests {
@@ -83,6 +86,36 @@ public final class PromiseTests {
         assert !finished.get();
     }
 
+    public IntStream unsizedIntStream(int size) {
+        AtomicInteger i = new AtomicInteger();
+        return IntStream.generate(i::getAndIncrement).limit(size);
+    }
+
+    @Test
+    public void testUnsizedIntStream() {
+        assert unsizedIntStream(1000).spliterator().estimateSize() == Long.MAX_VALUE;
+        assert Arrays.equals(unsizedIntStream(1000).toArray(), IntStream.range(0, 1000).toArray());
+    }
+
+    @Test
+    public void testDynamicCombine() {
+        var result = promises.combine(unsizedIntStream(1000).mapToObj(promises::resolve)).await();
+        assert result.equals(unsizedIntStream(1000).boxed().toList());
+    }
+
+    @Test
+    public void testDynamicCombine1() {
+        var result = promises.combine(IntStream.range(0, 1000).mapToObj(promises::resolve)).await();
+        assert result.equals(IntStream.range(0, 1000).boxed().toList());
+    }
+
+    @Test
+    public void testDynamicCombine2() {
+        var result = promises.combine(unsizedIntStream(1000)
+            .mapToObj(i -> promises.start().thenSupplyDelayedAsync(() -> i, 1000 - i, TimeUnit.MILLISECONDS))).await();
+        assert result.equals(unsizedIntStream(1000).boxed().toList());
+    }
+
     @Test
     public void testCombineUtil() throws TimeoutException, ExecutionException, InterruptedException {
         promises.all(