diff --git a/lib/PqExecutor.php b/lib/PqExecutor.php
index 6ee7266..d999927 100644
--- a/lib/PqExecutor.php
+++ b/lib/PqExecutor.php
@@ -2,7 +2,7 @@
 
 namespace Amp\Postgres;
 
-use Amp\{ CallableMaker, Coroutine, Deferred, Emitter, function pipe };
+use Amp\{ CallableMaker, Coroutine, Deferred, Emitter };
 use AsyncInterop\{ Loop, Promise };
 use pq;
 
@@ -82,7 +82,7 @@ class PqExecutor implements Executor {
         Loop::disable($this->await);
 
         $this->send = $this->callableFromInstanceMethod("send");
-        $this->fetch = $this->callableFromInstanceMethod("fetch");
+        $this->fetch = \Amp\coroutine($this->callableFromInstanceMethod("fetch"));
         $this->unlisten = $this->callableFromInstanceMethod("unlisten");
         $this->release = $this->callableFromInstanceMethod("release");
     }
@@ -248,7 +248,7 @@ class PqExecutor implements Executor {
                 $emitter->emit($notification);
             }));
         
-        return pipe($promise, function () use ($emitter, $channel): Listener {
+        return \Amp\pipe($promise, function () use ($emitter, $channel): Listener {
             $this->listeners[$channel] = $emitter;
             Loop::enable($this->poll);
             return new Listener($emitter->stream(), $channel, $this->unlisten);
diff --git a/lib/PqUnbufferedResult.php b/lib/PqUnbufferedResult.php
index bc8cc56..263cfbd 100644
--- a/lib/PqUnbufferedResult.php
+++ b/lib/PqUnbufferedResult.php
@@ -2,7 +2,7 @@
 
 namespace Amp\Postgres;
 
-use Amp\{ Coroutine, Producer };
+use Amp\Producer;
 use pq;
 
 class PqUnbufferedResult extends TupleResult implements Operation {
@@ -12,7 +12,7 @@ class PqUnbufferedResult extends TupleResult implements Operation {
     private $numCols;
     
     /**
-     * @param callable(): \Generator $fetch Coroutine function to fetch next result row.
+     * @param callable(): \AsyncInterop\Promise $fetch Function to fetch next result row.
      * @param \pq\Result $result PostgreSQL result object.
      */
     public function __construct(callable $fetch, pq\Result $result) {
@@ -21,7 +21,7 @@ class PqUnbufferedResult extends TupleResult implements Operation {
             $count = 0;
             try {
                 do {
-                    $next = new Coroutine($fetch()); // Request next result before current is consumed.
+                    $next = $fetch(); // Request next result before current is consumed.
                     ++$count;
                     yield $emit($result->fetchRow(pq\Result::FETCH_ASSOC));
                     $result = yield $next;