diff --git a/src/Version/Stability.php b/src/Version/Stability.php
index 5b715c7..e141cba 100644
--- a/src/Version/Stability.php
+++ b/src/Version/Stability.php
@@ -2,12 +2,10 @@
 
 namespace Version;
 
-use JsonSchema\Exception\InvalidArgumentException;
-
 class Stability
 {
 
-    const REGEX = '[-|_|\.]{0,1}([R|r][C|c]|pl|a|alpha|[B|b][E|e][T|t][A|a]|b|B|patch|stable|p)\.{0,1}(\d*)';
+    const REGEX = '[-|_|\.]{0,1}([R|r][C|c]|pl|a|alpha|[B|b][E|e][T|t][A|a]|b|B|patch|stable|p|[D|d][E|e][V|v]|[D|d])\.{0,1}(\d*)';
 
     /**
      * @var string
@@ -109,7 +107,7 @@ private function toInt( $stability )
             case 'patch':
                 return 6;
             default:
-                throw new InvalidArgumentException( 'Invalid stability: ' . $stability );
+                throw new \InvalidArgumentException( 'Invalid stability: ' . $stability );
         }
     }
 }
diff --git a/src/Version/Version.php b/src/Version/Version.php
index 7c0c1e7..e9d3c81 100644
--- a/src/Version/Version.php
+++ b/src/Version/Version.php
@@ -208,8 +208,8 @@ public function __toString()
             $version =
                 $this->major . '.' .
                 $this->minor . '.' .
-                $this->revision . '.' .
-                (int)$this->micro;
+                $this->revision;
+                if($this->micro !== null) $version .= '.' . (int)$this->micro;
         } else {
             $version = $this->major;
             if ($this->minor) $version .= '-' . $this->minor;