diff --git a/db-async-common/src/main/scala/com/github/mauricio/async/db/pool/SingleThreadedAsyncObjectPool.scala b/db-async-common/src/main/scala/com/github/mauricio/async/db/pool/SingleThreadedAsyncObjectPool.scala
index 49f60593..b4f25ae2 100644
--- a/db-async-common/src/main/scala/com/github/mauricio/async/db/pool/SingleThreadedAsyncObjectPool.scala
+++ b/db-async-common/src/main/scala/com/github/mauricio/async/db/pool/SingleThreadedAsyncObjectPool.scala
@@ -22,7 +22,7 @@ import com.github.mauricio.async.db.util.{Log, Worker}
 import java.util.concurrent.atomic.AtomicLong
 import java.util.{Timer, TimerTask}
 
-import scala.collection.mutable.{ArrayBuffer, Queue, Stack}
+import scala.collection.mutable.{ArrayBuffer, Queue}
 import scala.concurrent.{Future, Promise}
 import scala.util.{Failure, Success}
 
@@ -52,7 +52,7 @@ class SingleThreadedAsyncObjectPool[T](
   import SingleThreadedAsyncObjectPool.{Counter, log}
 
   private val mainPool = Worker()
-  private var poolables = new Stack[PoolableHolder[T]]()
+  private var poolables = List.empty[PoolableHolder[T]]
   private val checkouts = new ArrayBuffer[T](configuration.maxObjects)
   private val waitQueue = new Queue[Promise[T]]()
   private val timer = new Timer("async-object-pool-timer-" + Counter.incrementAndGet(), true)
@@ -171,7 +171,7 @@ class SingleThreadedAsyncObjectPool[T](
    */
 
   private def addBack(item: T, promise: Promise[AsyncObjectPool[T]]) {
-    this.poolables.push(new PoolableHolder[T](item))
+    this.poolables ::= new PoolableHolder[T](item)
 
     if (this.waitQueue.nonEmpty) {
       this.checkout(this.waitQueue.dequeue())
@@ -226,7 +226,9 @@ class SingleThreadedAsyncObjectPool[T](
         case e: Exception => promise.failure(e)
       }
     } else {
-      val item = this.poolables.pop().item
+      val h :: t = this.poolables
+      this.poolables = t
+      val item = h.item
       this.checkouts += item
       promise.success(item)
     }
diff --git a/postgresql-async/src/main/scala/com/github/mauricio/async/db/postgresql/column/ArrayDecoder.scala b/postgresql-async/src/main/scala/com/github/mauricio/async/db/postgresql/column/ArrayDecoder.scala
index d69eeba4..b62e9629 100644
--- a/postgresql-async/src/main/scala/com/github/mauricio/async/db/postgresql/column/ArrayDecoder.scala
+++ b/postgresql-async/src/main/scala/com/github/mauricio/async/db/postgresql/column/ArrayDecoder.scala
@@ -19,7 +19,7 @@ package com.github.mauricio.async.db.postgresql.column
 import com.github.mauricio.async.db.column.ColumnDecoder
 import com.github.mauricio.async.db.postgresql.util.{ArrayStreamingParserDelegate, ArrayStreamingParser}
 import scala.collection.IndexedSeq
-import scala.collection.mutable.{ArrayBuffer, Stack}
+import scala.collection.mutable.ArrayBuffer
 import com.github.mauricio.async.db.general.ColumnData
 import io.netty.buffer.{Unpooled, ByteBuf}
 import java.nio.charset.Charset
@@ -32,12 +32,13 @@ class ArrayDecoder(private val decoder: ColumnDecoder) extends ColumnDecoder {
     buffer.readBytes(bytes)
     val value = new String(bytes, charset)
 
-    val stack = new Stack[ArrayBuffer[Any]]()
+    var stack = List.empty[ArrayBuffer[Any]]
     var current: ArrayBuffer[Any] = null
     var result: IndexedSeq[Any] = null
     val delegate = new ArrayStreamingParserDelegate {
       override def arrayEnded {
-        result = stack.pop()
+        result = stack.head
+        stack = stack.tail
       }
 
       override def elementFound(element: String) {
@@ -63,7 +64,7 @@ class ArrayDecoder(private val decoder: ColumnDecoder) extends ColumnDecoder {
           case None => {}
         }
 
-        stack.push(current)
+        stack ::= current
       }
     }