diff --git a/src/Config.php b/src/Config.php
index 402b6e4..d2a0f00 100644
--- a/src/Config.php
+++ b/src/Config.php
@@ -30,13 +30,6 @@ class Config implements Countable, Iterator, ArrayAccess
      */
     protected $allowModifications;
 
-    /**
-     * Number of elements in configuration data.
-     *
-     * @var int
-     */
-    protected $count;
-
     /**
      * Data within the configuration.
      *
@@ -71,8 +64,6 @@ public function __construct(array $array, $allowModifications = false)
             } else {
                 $this->data[$key] = $value;
             }
-
-            $this->count++;
         }
     }
 
@@ -126,8 +117,6 @@ public function __set($name, $value)
             } else {
                 $this->data[$name] = $value;
             }
-
-            $this->count++;
         } else {
             throw new Exception\RuntimeException('Config is read only');
         }
@@ -200,7 +189,6 @@ public function __unset($name)
             throw new Exception\InvalidArgumentException('Config is read only');
         } elseif (isset($this->data[$name])) {
             unset($this->data[$name]);
-            $this->count--;
             $this->skipNextIteration = true;
         }
     }
@@ -213,7 +201,7 @@ public function __unset($name)
      */
     public function count()
     {
-        return $this->count;
+        return count($this->data);
     }
 
     /**
@@ -360,8 +348,6 @@ public function merge(Config $merge)
                 } else {
                     $this->data[$key] = $value;
                 }
-
-                $this->count++;
             }
         }
 
diff --git a/test/ConfigTest.php b/test/ConfigTest.php
index bcf2764..9554636 100644
--- a/test/ConfigTest.php
+++ b/test/ConfigTest.php
@@ -184,6 +184,17 @@ public function testCountAfterMerge()
         $this->assertEquals(count($data->toArray()), $data->count());
     }
 
+    public function testCountWithDoubleKeys()
+    {
+        $config = new Config(array(), true);
+
+        $config->foo = 1;
+        $config->foo = 2;
+        $this->assertSame(2, $config->foo);
+        $this->assertCount(1, $config->toArray());
+        $this->assertCount(1, $config);
+    }
+
     public function testIterator()
     {
         // top level