diff --git a/pushy/src/main/java/com/eatthepath/pushy/apns/ApnsChannelPool.java b/pushy/src/main/java/com/eatthepath/pushy/apns/ApnsChannelPool.java
index f1c3ebd09..55a8aefb2 100644
--- a/pushy/src/main/java/com/eatthepath/pushy/apns/ApnsChannelPool.java
+++ b/pushy/src/main/java/com/eatthepath/pushy/apns/ApnsChannelPool.java
@@ -178,6 +178,14 @@ private void acquireWithinEventExecutor(final Promise<Channel> acquirePromise) {
                         this.acquireWithinEventExecutor(acquirePromise);
                     }
                 } else {
+                    // If the deferred acquirePromise is cancelled, remove it from pendingAcquisitionPromises
+                    // to allow garbage collection.
+                    acquirePromise.addListener(future -> {
+                        if (future.isCancelled()) {
+                            pendingAcquisitionPromises.remove(acquirePromise);
+                        }
+                    });
+
                     // We don't have any connections ready to go, and don't have any more capacity to create new
                     // channels. Add this acquisition to the queue waiting for channels to become available.
                     pendingAcquisitionPromises.add(acquirePromise);
diff --git a/pushy/src/main/java/com/eatthepath/pushy/apns/ApnsClient.java b/pushy/src/main/java/com/eatthepath/pushy/apns/ApnsClient.java
index 6e119448c..c06703e0c 100644
--- a/pushy/src/main/java/com/eatthepath/pushy/apns/ApnsClient.java
+++ b/pushy/src/main/java/com/eatthepath/pushy/apns/ApnsClient.java
@@ -184,7 +184,8 @@ public <T extends ApnsPushNotification> PushNotificationFuture<T, PushNotificati
         if (!this.isClosed.get()) {
             final long start = System.nanoTime();
 
-            this.channelPool.acquire().addListener((GenericFutureListener<Future<Channel>>) acquireFuture -> {
+            Future<Channel> acquirePromise = this.channelPool.acquire();
+            acquirePromise.addListener((GenericFutureListener<Future<Channel>>) acquireFuture -> {
                 if (acquireFuture.isSuccess()) {
                     final Channel channel = acquireFuture.getNow();
 
@@ -207,6 +208,12 @@ public <T extends ApnsPushNotification> PushNotificationFuture<T, PushNotificati
                     ApnsClient.this.metricsListener.handleNotificationAcknowledged(response, end - start);
                 } else {
                     ApnsClient.this.metricsListener.handleWriteFailure(notification.getTopic());
+
+                    // Try cancel acquirePromise if responseFuture fails (e.g. TimeoutException)
+                    // before acquirePromise gets resolved.
+                    if (acquirePromise.isCancellable()) {
+                        acquirePromise.cancel(true);
+                    }
                 }
             });
         } else {