diff --git a/build.gradle b/build.gradle
index c821280..59932c5 100644
--- a/build.gradle
+++ b/build.gradle
@@ -6,7 +6,7 @@ plugins {
 
 subprojects {
     group = 'dev.tommyjs'
-    version = '2.5.3'
+    version = '2.5.4'
 
     apply plugin: 'java-library'
     apply plugin: 'com.github.johnrengelman.shadow'
diff --git a/futur-api/src/main/java/dev/tommyjs/futur/joiner/CompletionJoiner.java b/futur-api/src/main/java/dev/tommyjs/futur/joiner/CompletionJoiner.java
index 2faeaf7..fd9e682 100644
--- a/futur-api/src/main/java/dev/tommyjs/futur/joiner/CompletionJoiner.java
+++ b/futur-api/src/main/java/dev/tommyjs/futur/joiner/CompletionJoiner.java
@@ -20,12 +20,12 @@ public class CompletionJoiner extends PromiseJoiner<Promise<?>, Void, Void, List
     }
 
     @Override
-    protected Void getChildKey(Promise<?> value) {
+    protected Void getChildKey(@NotNull Promise<?> value) {
         return null;
     }
 
     @Override
-    protected @NotNull Promise<Void> getChildPromise(Promise<?> value) {
+    protected @NotNull Promise<Void> getChildPromise(@NotNull Promise<?> value) {
         //noinspection unchecked
         return (Promise<Void>) value;
     }
diff --git a/futur-api/src/main/java/dev/tommyjs/futur/joiner/MappedResultJoiner.java b/futur-api/src/main/java/dev/tommyjs/futur/joiner/MappedResultJoiner.java
index a2a5ad9..4b679cc 100644
--- a/futur-api/src/main/java/dev/tommyjs/futur/joiner/MappedResultJoiner.java
+++ b/futur-api/src/main/java/dev/tommyjs/futur/joiner/MappedResultJoiner.java
@@ -5,6 +5,7 @@ import dev.tommyjs.futur.promise.PromiseCompletion;
 import dev.tommyjs.futur.promise.PromiseFactory;
 import dev.tommyjs.futur.util.ConcurrentResultArray;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.*;
 
@@ -20,12 +21,12 @@ public class MappedResultJoiner<K, V> extends PromiseJoiner<Map.Entry<K, Promise
     }
 
     @Override
-    protected K getChildKey(Map.Entry<K, Promise<V>> entry) {
+    protected K getChildKey(@NotNull Map.Entry<K, Promise<V>> entry) {
         return entry.getKey();
     }
 
     @Override
-    protected @NotNull Promise<V> getChildPromise(Map.Entry<K, Promise<V>> entry) {
+    protected @Nullable Promise<V> getChildPromise(@NotNull Map.Entry<K, Promise<V>> entry) {
         return entry.getValue();
     }
 
diff --git a/futur-api/src/main/java/dev/tommyjs/futur/joiner/PromiseJoiner.java b/futur-api/src/main/java/dev/tommyjs/futur/joiner/PromiseJoiner.java
index 56b465f..c33a39d 100644
--- a/futur-api/src/main/java/dev/tommyjs/futur/joiner/PromiseJoiner.java
+++ b/futur-api/src/main/java/dev/tommyjs/futur/joiner/PromiseJoiner.java
@@ -6,6 +6,7 @@ import dev.tommyjs.futur.promise.PromiseCompletion;
 import dev.tommyjs.futur.promise.PromiseFactory;
 import dev.tommyjs.futur.util.PromiseUtil;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 import java.util.Iterator;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -18,35 +19,40 @@ public abstract class PromiseJoiner<T, Key, Value, Result> {
         this.joined = factory.unresolved();
     }
 
-    protected abstract Key getChildKey(T value);
+    protected abstract Key getChildKey(@NotNull T value);
 
-    protected abstract @NotNull Promise<Value> getChildPromise(T value);
+    protected abstract @Nullable Promise<Value> getChildPromise(@NotNull T value);
 
     protected abstract void onChildComplete(int index, Key key, @NotNull PromiseCompletion<Value> completion);
 
     protected abstract Result getResult();
 
-    protected void join(@NotNull Iterator<T> promises) {
+    protected void join(@NotNull Iterator<@Nullable T> promises) {
+        assert !joined.isCompleted();
+
         AtomicInteger count = new AtomicInteger();
 
         int i = 0;
         do {
-            if (joined.isCompleted()) {
-                promises.forEachRemaining(v -> getChildPromise(v).cancel());
-                return;
+            T value = promises.next();
+            if (value == null) {
+                continue;
             }
 
-            T value = promises.next();
-            Promise<Value> p = getChildPromise(value);
-            if (!p.isCompleted()) {
-                PromiseUtil.cancelOnComplete(joined, p);
+            Promise<Value> promise = getChildPromise(value);
+            if (promise == null) {
+                continue;
+            }
+
+            if (!promise.isCompleted()) {
+                PromiseUtil.cancelOnComplete(joined, promise);
             }
 
             count.incrementAndGet();
             Key key = getChildKey(value);
             int index = i++;
 
-            p.addAsyncListener(res -> {
+            promise.addAsyncListener(res -> {
                 onChildComplete(index, key, res);
                 if (res.isError()) {
                     assert res.getException() != null;
diff --git a/futur-api/src/main/java/dev/tommyjs/futur/joiner/ResultJoiner.java b/futur-api/src/main/java/dev/tommyjs/futur/joiner/ResultJoiner.java
index 3f53887..b3009e5 100644
--- a/futur-api/src/main/java/dev/tommyjs/futur/joiner/ResultJoiner.java
+++ b/futur-api/src/main/java/dev/tommyjs/futur/joiner/ResultJoiner.java
@@ -20,12 +20,12 @@ public class ResultJoiner<T> extends PromiseJoiner<Promise<T>, Void, T, List<T>>
     }
 
     @Override
-    protected Void getChildKey(Promise<T> value) {
+    protected Void getChildKey(@NotNull Promise<T> value) {
         return null;
     }
 
     @Override
-    protected @NotNull Promise<T> getChildPromise(Promise<T> value) {
+    protected @NotNull Promise<T> getChildPromise(@NotNull Promise<T> value) {
         return value;
     }
 
diff --git a/futur-api/src/main/java/dev/tommyjs/futur/joiner/VoidJoiner.java b/futur-api/src/main/java/dev/tommyjs/futur/joiner/VoidJoiner.java
index 56a58d5..5584150 100644
--- a/futur-api/src/main/java/dev/tommyjs/futur/joiner/VoidJoiner.java
+++ b/futur-api/src/main/java/dev/tommyjs/futur/joiner/VoidJoiner.java
@@ -15,12 +15,12 @@ public class VoidJoiner extends PromiseJoiner<Promise<?>, Void, Void, Void> {
     }
 
     @Override
-    protected Void getChildKey(Promise<?> value) {
+    protected Void getChildKey(@NotNull Promise<?> value) {
         return null;
     }
 
     @Override
-    protected @NotNull Promise<Void> getChildPromise(Promise<?> value) {
+    protected @NotNull Promise<Void> getChildPromise(@NotNull Promise<?> value) {
         //noinspection unchecked
         return (Promise<Void>) value;
     }
diff --git a/futur-api/src/main/java/dev/tommyjs/futur/promise/AbstractPromiseFactory.java b/futur-api/src/main/java/dev/tommyjs/futur/promise/AbstractPromiseFactory.java
index 91688fb..a8cf488 100644
--- a/futur-api/src/main/java/dev/tommyjs/futur/promise/AbstractPromiseFactory.java
+++ b/futur-api/src/main/java/dev/tommyjs/futur/promise/AbstractPromiseFactory.java
@@ -70,7 +70,7 @@ public abstract class AbstractPromiseFactory implements PromiseFactory {
             return resolve(Collections.emptyList());
         }
 
-        return new ResultJoiner<>(this, promises, expectedSize).joined();
+        return new ResultJoiner<V>(this, promises, expectedSize).joined();
     }
 
     @Override
diff --git a/futur-api/src/main/java/dev/tommyjs/futur/promise/PromiseFactory.java b/futur-api/src/main/java/dev/tommyjs/futur/promise/PromiseFactory.java
index 6780e16..4da6302 100644
--- a/futur-api/src/main/java/dev/tommyjs/futur/promise/PromiseFactory.java
+++ b/futur-api/src/main/java/dev/tommyjs/futur/promise/PromiseFactory.java
@@ -183,7 +183,7 @@ public interface PromiseFactory {
      * @param promises the input promises
      * @return the combined promise
      */
-    default <K, V> @NotNull Promise<Map<K, V>> combineMapped(@NotNull Map.Entry<K, Promise<V>>... promises) {
+    default <K, V> @NotNull Promise<Map<K, V>> combineMapped(@Nullable Map.Entry<K, Promise<V>>... promises) {
         return combineMapped(Arrays.spliterator(promises));
     }
 
@@ -298,7 +298,7 @@ public interface PromiseFactory {
      * @param promises the input promises
      * @return the combined promise
      */
-    default <V> @NotNull Promise<List<V>> combine(@NotNull Promise<V>... promises) {
+    default <V> @NotNull Promise<List<V>> combine(@Nullable Promise<V>... promises) {
         return combine(Arrays.spliterator(promises));
     }
 
@@ -352,7 +352,7 @@ public interface PromiseFactory {
      * @param promises the input promises
      * @return the combined promise
      */
-    default @NotNull Promise<List<PromiseCompletion<?>>> allSettled(@NotNull Promise<?>... promises) {
+    default @NotNull Promise<List<PromiseCompletion<?>>> allSettled(@Nullable Promise<?>... promises) {
         return allSettled(Arrays.spliterator(promises));
     }
 
@@ -398,7 +398,7 @@ public interface PromiseFactory {
      * @param promises the input promises
      * @return the combined promise
      */
-    default @NotNull Promise<Void> all(@NotNull Promise<?>... promises) {
+    default @NotNull Promise<Void> all(@Nullable Promise<?>... promises) {
         return all(Arrays.asList(promises).iterator());
     }
 
@@ -482,7 +482,7 @@ public interface PromiseFactory {
      * @param ignoreErrors whether to ignore promises that complete exceptionally
      * @return the combined promise
      */
-    default <V> @NotNull Promise<V> race(boolean ignoreErrors, @NotNull Promise<V>... promises) {
+    default <V> @NotNull Promise<V> race(boolean ignoreErrors, @Nullable Promise<V>... promises) {
         return race(Arrays.asList(promises), ignoreErrors);
     }
 
@@ -494,7 +494,7 @@ public interface PromiseFactory {
      * @param promises the input promises
      * @return the combined promise
      */
-    default <V> @NotNull Promise<V> race(@NotNull Promise<V>... promises) {
+    default <V> @NotNull Promise<V> race(@Nullable Promise<V>... promises) {
         return race(false, promises);
     }
 
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 cbe1983..c9a47de 100644
--- a/futur-api/src/test/java/dev/tommyjs/futur/PromiseTests.java
+++ b/futur-api/src/test/java/dev/tommyjs/futur/PromiseTests.java
@@ -8,6 +8,7 @@ import org.junit.jupiter.api.Test;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import java.util.AbstractMap;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
@@ -116,6 +117,19 @@ public final class PromiseTests {
         assert result.equals(unsizedIntStream(1000).boxed().toList());
     }
 
+    @Test
+    public void testCombineNull() {
+        var result1 = promises.combine(Arrays.asList(null, null, null)).await();
+        var result2 = promises.combineMapped(Arrays.asList(null, null, null)).await();
+        var result3 = promises.combineMapped(List.of(new AbstractMap.SimpleEntry<>(null, null))).await();
+        var result4 = promises.combineMapped(List.of(new AbstractMap.SimpleEntry<>(null, promises.resolve(true)))).await();
+
+        assert result1.isEmpty();
+        assert result2.isEmpty();
+        assert result3.isEmpty();
+        assert result4.get(null) == true;
+    }
+
     @Test
     public void testCombineUtil() throws TimeoutException, ExecutionException, InterruptedException {
         promises.all(