diff --git a/src/main/java/tk/draganczuk/url/Routes.java b/src/main/java/tk/draganczuk/url/Routes.java
index 5ce2c2d..f4477a5 100644
--- a/src/main/java/tk/draganczuk/url/Routes.java
+++ b/src/main/java/tk/draganczuk/url/Routes.java
@@ -34,7 +34,7 @@ public class Routes {
 			return urlRepository.addUrl(longUrl, shortUrl);
 		} else {
 			res.status(HttpStatus.BAD_REQUEST_400);
-			return "shortUrl not valid ([a-z0-9]+)";
+			return "shortUrl not valid ([a-z0-9-_]+)";
 		}
 	}
 
diff --git a/src/main/java/tk/draganczuk/url/Utils.java b/src/main/java/tk/draganczuk/url/Utils.java
index 14e71d4..8410e5a 100644
--- a/src/main/java/tk/draganczuk/url/Utils.java
+++ b/src/main/java/tk/draganczuk/url/Utils.java
@@ -6,7 +6,7 @@ import java.util.regex.Pattern;
 public class Utils {
 	private static final Random random = new Random(System.currentTimeMillis());
 
-	private static final String SHORT_URL_PATTERN = "[a-z0-9_-]+";
+	private static final String SHORT_URL_PATTERN = "[a-z0-9-_]+";
 	private static final Pattern PATTERN = Pattern.compile(SHORT_URL_PATTERN);
 
 	public static String randomString() {