diff --git a/src/Intervention/Image/Gd/Commands/LimitColorsCommand.php b/src/Intervention/Image/Gd/Commands/LimitColorsCommand.php
index dea31b50..a2889bec 100644
--- a/src/Intervention/Image/Gd/Commands/LimitColorsCommand.php
+++ b/src/Intervention/Image/Gd/Commands/LimitColorsCommand.php
@@ -39,7 +39,7 @@ class LimitColorsCommand extends \Intervention\Image\Commands\AbstractCommand
         // copy original image
         imagecopy($resource, $image->getCore(), 0, 0, 0, 0, $size->width, $size->height);
 
-        if ($count <= 256) {
+        if (is_numeric($count) && $count <= 256) {
             // decrease colors
             imagetruecolortopalette($resource, true, $count);
         }
diff --git a/tests/GdSystemTest.php b/tests/GdSystemTest.php
index 2499a8ee..8ec310f8 100644
--- a/tests/GdSystemTest.php
+++ b/tests/GdSystemTest.php
@@ -1076,6 +1076,16 @@ class GdSystemTest extends PHPUnit_Framework_TestCase
         $this->assertColorAtPosition('#e40214', $img, 16, 21);
     }
 
+    public function testLimitColorsNullWithMatte()
+    {
+        $img = $this->manager()->make('tests/images/tile.png');
+        $img->limitColors(null, '#ff00ff');
+        $this->assertColorAtPosition('#b4e000', $img, 0, 0);
+        $this->assertColorAtPosition('#445160', $img, 8, 8);
+        $this->assertColorAtPosition('#ff00ff', $img, 0, 8);
+        $this->assertColorAtPosition('#ff00ff', $img, 15, 0);
+    }
+
     public function testPickColorFromTrueColor()
     {
         $img = $this->manager()->make('tests/images/star.png');
diff --git a/tests/ImagickSystemTest.php b/tests/ImagickSystemTest.php
index 8accab48..0ec1db41 100644
--- a/tests/ImagickSystemTest.php
+++ b/tests/ImagickSystemTest.php
@@ -1049,6 +1049,16 @@ class ImagickSystemTest extends PHPUnit_Framework_TestCase
         $this->assertColorAtPosition('#e70012', $img, 16, 21);
     }
 
+    public function testLimitColorsNullWithMatte()
+    {
+        $img = $this->manager()->make('tests/images/tile.png');
+        $img->limitColors(null, '#ff00ff');
+        $this->assertColorAtPosition('#b4e000', $img, 0, 0);
+        $this->assertColorAtPosition('#445160', $img, 8, 8);
+        $this->assertColorAtPosition('#ff00ff', $img, 0, 8);
+        $this->assertColorAtPosition('#ff00ff', $img, 15, 0);
+    }
+
     public function testPickColorFromTrueColor()
     {
         $img = $this->manager()->make('tests/images/star.png');