diff --git a/src/Phpml/Pipeline.php b/src/Phpml/Pipeline.php
index 2c2d984..f230db3 100644
--- a/src/Phpml/Pipeline.php
+++ b/src/Phpml/Pipeline.php
@@ -67,10 +67,7 @@ class Pipeline implements Estimator
      */
     public function train(array $samples, array $targets)
     {
-        foreach ($this->transformers as $transformer) {
-            $transformer->transform($samples);
-        }
-
+        $this->transformSamples($samples);
         $this->estimator->train($samples, $targets);
     }
 
@@ -81,6 +78,18 @@ class Pipeline implements Estimator
      */
     public function predict(array $samples)
     {
+        $this->transformSamples($samples);
+
         return $this->estimator->predict($samples);
     }
+
+    /**
+     * @param array $samples
+     */
+    private function transformSamples(array &$samples)
+    {
+        foreach ($this->transformers as $transformer) {
+            $transformer->transform($samples);
+        }
+    }
 }
diff --git a/src/Phpml/Preprocessing/Preprocessor.php b/src/Phpml/Preprocessing/Preprocessor.php
index ff5530e..ae70941 100644
--- a/src/Phpml/Preprocessing/Preprocessor.php
+++ b/src/Phpml/Preprocessing/Preprocessor.php
@@ -8,5 +8,4 @@ use Phpml\Transformer;
 
 interface Preprocessor extends Transformer
 {
-
 }
diff --git a/tests/Phpml/PipelineTest.php b/tests/Phpml/PipelineTest.php
index b1d5bf7..4e5815b 100644
--- a/tests/Phpml/PipelineTest.php
+++ b/tests/Phpml/PipelineTest.php
@@ -43,7 +43,7 @@ class PipelineTest extends \PHPUnit_Framework_TestCase
         $targets = [
             4,
             1,
-            4
+            4,
         ];
 
         $pipeline = new Pipeline($transformers, $estimator);
@@ -53,5 +53,4 @@ class PipelineTest extends \PHPUnit_Framework_TestCase
 
         $this->assertEquals(4, $predicted[0]);
     }
-
 }