diff --git a/src/FFMpeg/Media/Audio.php b/src/FFMpeg/Media/Audio.php
index 605345b..95d4fd0 100644
--- a/src/FFMpeg/Media/Audio.php
+++ b/src/FFMpeg/Media/Audio.php
@@ -108,6 +108,7 @@ class Audio extends AbstractStreamableMedia
      *
      * @param  integer $width
      * @param  integer $height
+     * @param array $colors Array of colors for ffmpeg to use. Color format is #000000 (RGB hex string with #)
      * @return Waveform
      */
     public function waveform($width = 640, $height = 120, $colors = [Waveform::DEFAULT_COLOR])
diff --git a/src/FFMpeg/Media/Waveform.php b/src/FFMpeg/Media/Waveform.php
index 84ccc05..ae66b49 100644
--- a/src/FFMpeg/Media/Waveform.php
+++ b/src/FFMpeg/Media/Waveform.php
@@ -79,13 +79,14 @@ class Waveform extends AbstractMediaType
      * example #FFFFFF or #000000. By default the color is set to black. Keep in mind that if you save the waveform
      * as jpg file, it will appear completely black and to avoid this you can set the waveform color to white (#FFFFFF).
      * Saving waveforms to png is strongly suggested.
+     *
      * @param array $colors
      */
     public function setColors(array $colors)
     {
         foreach ($colors as $row => $value)
         {
-            if ($value{0} != '#' || strlen($value) != 7)
+            if (!preg_match_all('/^#(?:[0-9a-fA-F]{6})$/', $value))
             {
                 //invalid color
                 unset($colors[$row]);
@@ -102,6 +103,7 @@ class Waveform extends AbstractMediaType
      * Returns an array of colors that will be passed to ffmpeg to use for waveform generation. Colors are applied ONLY
      * to the waveform. Background cannot be controlled that easily and it is probably easier to save the waveform
      * as a transparent png file and then add background of choice.
+     *
      * @return array
      */
     public function getColors()
@@ -111,6 +113,7 @@ class Waveform extends AbstractMediaType
 
     /**
      * Compiles the selected colors into a string, using a pipe separator.
+     *
      * @return string
      */
     protected function compileColors()
diff --git a/tests/Unit/Media/WaveformTest.php b/tests/Unit/Media/WaveformTest.php
index 49fda37..5d13c2e 100644
--- a/tests/Unit/Media/WaveformTest.php
+++ b/tests/Unit/Media/WaveformTest.php
@@ -61,7 +61,7 @@ class WaveformTest extends AbstractMediaTestCase
         return array(
             array(
                 array(
-                    '-i', NULL, '-filter_complex',
+                    '-y', '-i', NULL, '-filter_complex',
                     'showwavespic=colors=#FFFFFF:s=640x120',
                     '-frames:v', '1',
                 ),