diff --git a/.travis.yml b/.travis.yml
index c30efee..3ddd7c1 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -12,16 +12,24 @@ matrix:
     - php: nightly
   fast_finish: true
 
-before_script:
-  - composer self-update
-  - composer install
+env:
+  - DEPS=lowest
+  - DEPS=highest
+
+install:
+  - if [ "$DEPS" = "lowest" ]; then
+      composer update -n --prefer-source --prefer-lowest;
+    else
+      composer update -n --prefer-source;
+    fi;
+  - composer show
 
 script:
   - phpdbg -qrr vendor/bin/phpunit --coverage-text --coverage-clover build/logs/clover.xml
   - php vendor/bin/php-cs-fixer --diff --dry-run -v fix
 
 after_script:
-  - composer require satooshi/php-coveralls:dev-master
+  - composer require satooshi/php-coveralls dev-master
   - php vendor/bin/coveralls -v
 
 cache:
diff --git a/lib/DefaultResolver.php b/lib/DefaultResolver.php
index b723480..a5c85e9 100644
--- a/lib/DefaultResolver.php
+++ b/lib/DefaultResolver.php
@@ -440,9 +440,9 @@ class DefaultResolver implements Resolver {
         if (\strpos($uri, "://") !== false) {
             return $uri;
         }
-        if (($colonPos = \strrpos(":", $uri)) !== false) {
+        if (($colonPos = \strrpos($uri, ":")) !== false) {
             $addr = \substr($uri, 0, $colonPos);
-            $port = \substr($uri, $colonPos);
+            $port = \substr($uri, $colonPos + 1);
         } else {
             $addr = $uri;
             $port = 53;