diff --git a/Converter/SemverConverter.php b/Converter/SemverConverter.php
index be1cf1f6..4cb4b0ae 100644
--- a/Converter/SemverConverter.php
+++ b/Converter/SemverConverter.php
@@ -28,7 +28,7 @@ public function convertVersion($version)
         }
 
         $version = str_replace('–', '-', $version);
-        $prefix = preg_match('/^[a-z]/', $version) ? substr($version, 0, 1) : '';
+        $prefix = preg_match('/^[a-z]/', $version) && 0 !== strpos($version, 'dev-') ? substr($version, 0, 1) : '';
         $version = substr($version, strlen($prefix));
         $version = SemverUtil::convertVersionMetadata($version);
         $version = SemverUtil::convertDateVersion($version);