diff --git a/bitcoin b/bitcoin
new file mode 120000
index 000000000..f3c139563
--- /dev/null
+++ b/bitcoin
@@ -0,0 +1 @@
+bitcoin
\ No newline at end of file
diff --git a/composer.json b/composer.json
index 41193ac70..d7acb28fe 100644
--- a/composer.json
+++ b/composer.json
@@ -27,7 +27,7 @@
     "pleonasm/merkle-tree": "1.0.0",
     "composer/semver": "^1.4.0|^3.2.0",
     "lastguest/murmurhash": "v2.0.0",
-    "mdanter/ecc": "^0.5.0",
+    "mdanter/ecc": ">0.5.0",
     "bitwasp/buffertools": "^0.5.0",
     "bitwasp/bech32": "^0.0.1"
   },
diff --git a/src/Transaction/Mutator/AbstractCollectionMutator.php b/src/Transaction/Mutator/AbstractCollectionMutator.php
index 222e69d03..81841249a 100644
--- a/src/Transaction/Mutator/AbstractCollectionMutator.php
+++ b/src/Transaction/Mutator/AbstractCollectionMutator.php
@@ -3,117 +3,87 @@
 declare(strict_types=1);
 
 namespace BitWasp\Bitcoin\Transaction\Mutator;
+use ArrayAccess;
+use Countable;
+use Iterator;
+use SplFixedArray;
 
-abstract class AbstractCollectionMutator implements \Iterator, \ArrayAccess, \Countable
+abstract class AbstractCollectionMutator implements Iterator, ArrayAccess, Countable
 {
-    /**
-     * @var \SplFixedArray
-     */
     protected $set;
+    private $position;
+
+    public function __construct(int $size)
+    {
+        $this->set = new SplFixedArray($size);
+        $this->position = 0;
+    }
 
-    /**
-     * @return array
-     */
     public function all(): array
     {
         return $this->set->toArray();
     }
 
-    /**
-     * @return bool
-     */
     public function isNull(): bool
     {
         return count($this->set) === 0;
     }
 
-    /**
-     * @return int
-     */
-    public function count(): int
-    {
-        return $this->set->count();
-    }
-
-    /**
-     *
-     */
     public function rewind()
     {
-        $this->set->rewind();
+        $this->position = 0;
     }
 
-    /**
-     * @return mixed
-     */
     public function current()
     {
-        return $this->set->current();
+        return $this->set[$this->position];
     }
 
-    /**
-     * @return int
-     */
     public function key()
     {
-        return $this->set->key();
+        return $this->position;
     }
 
-    /**
-     *
-     */
     public function next()
     {
-        $this->set->next();
+        $this->position++;
     }
 
-    /**
-     * @return bool
-     */
     public function valid()
     {
-        return $this->set->valid();
+        return isset($this->set[$this->position]);
     }
 
-    /**
-     * @param int $offset
-     * @return bool
-     */
     public function offsetExists($offset)
     {
-        return $this->set->offsetExists($offset);
+        return isset($this->set[$offset]);
     }
 
-    /**
-     * @param int $offset
-     */
-    public function offsetUnset($offset)
+    public function offsetGet($offset)
     {
-        if (!$this->offsetExists($offset)) {
-            throw new \InvalidArgumentException('Offset does not exist');
-        }
-
-        $this->set->offsetUnset($offset);
+        return $this->set[$offset];
     }
 
-    /**
-     * @param int $offset
-     * @return mixed
-     */
-    public function offsetGet($offset)
+    public function offsetSet($offset, $value)
     {
         if (!$this->set->offsetExists($offset)) {
             throw new \OutOfRangeException('Nothing found at this offset');
         }
-        return $this->set->offsetGet($offset);
+
+        $this->set[$offset] = $value;
     }
 
-    /**
-     * @param int $offset
-     * @param mixed $value
-     */
-    public function offsetSet($offset, $value)
+    public function offsetUnset($offset)
     {
-        $this->set->offsetSet($offset, $value);
+        if (!$this->offsetExists($offset)) {
+            throw new \InvalidArgumentException('Offset does not exist');
+        }
+
+        unset($this->set[$offset]);
+    }
+
+    public function count()
+    {
+        return $this->set->count();
     }
 }
diff --git a/src/Transaction/Mutator/InputCollectionMutator.php b/src/Transaction/Mutator/InputCollectionMutator.php
index 8832942d2..b571a3017 100644
--- a/src/Transaction/Mutator/InputCollectionMutator.php
+++ b/src/Transaction/Mutator/InputCollectionMutator.php
@@ -23,14 +23,6 @@ public function __construct(array $inputs)
         $this->set = \SplFixedArray::fromArray($set, false);
     }
 
-    /**
-     * @return InputMutator
-     */
-    public function current(): InputMutator
-    {
-        return $this->set->current();
-    }
-
     /**
      * @param int $offset
      * @return InputMutator