diff --git a/.travis.yml b/.travis.yml
index 1a61c2a..9c4af29 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,24 +1,21 @@
 # See https://github.com/silverstripe/silverstripe-travis-support for setup details
 
-sudo: false
+dist: trusty
 
 language: php
 
-php:
-  - 5.4
-  - 5.5
-
-env:
-  - DB=MYSQL CORE_RELEASE=3.5
-
 matrix:
   include:
-    - php: 5.6
-      env: DB=MYSQL CORE_RELEASE=3
-    - php: 5.6
-      env: DB=PGSQL CORE_RELEASE=3.4
-    - php: 7.1
+    - php: '5.6'
       env: DB=MYSQL CORE_RELEASE=3.6
+    - php: '7.0'
+      env: DB=PGSQL CORE_RELEASE=3.7
+    - php: '7.1'
+      env: DB=MYSQL CORE_RELEASE=3.7
+    - php: '7.2'
+      env: DB=MYSQL CORE_RELEASE=3.7
+    - php: '7.3'
+      env: DB=MYSQL CORE_RELEASE=3.7
 
 before_script:
   - composer self-update || true
diff --git a/code/form/WidgetAreaEditor.php b/code/form/WidgetAreaEditor.php
index 8c7363b..d5139f7 100644
--- a/code/form/WidgetAreaEditor.php
+++ b/code/form/WidgetAreaEditor.php
@@ -42,17 +42,17 @@ class WidgetAreaEditor extends FormField
         $widgets= new ArrayList();
 
         foreach ($this->widgetClasses as $widgetClass) {
-            $classes = ClassInfo::subclassesFor($widgetClass);
+            $classes = ClassInfo::subclassesFor($widgetClass) ?: array();
 
             if (isset($classes['Widget'])) {
                 unset($classes['Widget']);
             } elseif (isset($classes[0]) && $classes[0] == 'Widget') {
                 unset($classes[0]);
             }
-            
+
             foreach ($classes as $class) {
                 $available = Config::inst()->get($class, 'only_available_in');
-                
+
                 if (!empty($available) && is_array($available)) {
                     if (in_array($this->Name, $available)) {
                         $widgets->push(singleton($class));
@@ -62,7 +62,7 @@ class WidgetAreaEditor extends FormField
                 }
             }
         }
-        
+
         return $widgets;
     }
 
diff --git a/composer.json b/composer.json
index e83644e..197792f 100644
--- a/composer.json
+++ b/composer.json
@@ -14,7 +14,7 @@
 		"silverstripe/cms": "^3.2"
 	},
 	"require-dev": {
-		"phpunit/PHPUnit": "~3.7@stable"
+		"phpunit/phpunit": "^5.7"
 	},
 	"extra": {
 		"branch-alias": {