diff --git a/include/faabric/util/queue.h b/include/faabric/util/queue.h
index 2ad6c25e8..0de408ebc 100644
--- a/include/faabric/util/queue.h
+++ b/include/faabric/util/queue.h
@@ -145,6 +145,10 @@ template<typename T>
 class SpscQueue
 {
   public:
+    SpscQueue(int capacity) : mq(capacity) {};
+
+    SpscQueue() : mq(DEFAULT_QUEUE_SIZE) {};
+
     void enqueue(T value, long timeoutMs = DEFAULT_QUEUE_TIMEOUT_MS)
     {
         if (!mq.push(value)) {
@@ -164,7 +168,6 @@ class SpscQueue
             writerWaiting.store(false, std::memory_order_relaxed);
         }
 
-        // For this to work well, I'd have to take a lock before notify_one
         if (readerWaiting.load(std::memory_order_relaxed)) {
             UniqueLock lock(mx);
             notEmptyNotifier.notify_one();
@@ -202,15 +205,21 @@ class SpscQueue
 
     T* peek(long timeoutMs = DEFAULT_QUEUE_TIMEOUT_MS)
     {
-        while (mq.read_available() <= 0) {
+        if (mq.read_available() == 0) {
             UniqueLock lock(mx);
 
-            std::cv_status returnVal = notEmptyNotifier.wait_for(
-              lock, std::chrono::milliseconds(timeoutMs));
+            readerWaiting.store(true, std::memory_order_relaxed);
 
-            if (returnVal == std::cv_status::timeout) {
-                throw QueueTimeoutException("Timeout waiting for peek");
+            while (mq.read_available() == 0) {
+                std::cv_status returnVal = notEmptyNotifier.wait_for(
+                  lock, std::chrono::milliseconds(timeoutMs));
+
+                if (returnVal == std::cv_status::timeout) {
+                    throw QueueTimeoutException("Timeout waiting for dequeue");
+                }
             }
+
+            readerWaiting.store(false, std::memory_order_relaxed);
         }
 
         return &mq.front();
@@ -219,9 +228,7 @@ class SpscQueue
     long size() { return mq.read_available(); }
 
   private:
-    boost::lockfree::spsc_queue<T,
-                                boost::lockfree::capacity<DEFAULT_QUEUE_SIZE>>
-      mq;
+    boost::lockfree::spsc_queue<T> mq;
     std::mutex mx;
     std::atomic<bool> writerWaiting = false;
     std::condition_variable notEmptyNotifier;