diff --git a/composer.json b/composer.json
index bcde9d0..529e972 100644
--- a/composer.json
+++ b/composer.json
@@ -12,6 +12,12 @@
 		"silvershop/core": "3.x-dev",
         "symbiote/silverstripe-gridfieldextensions": "*"
 	},
+    "require-dev": {
+        "phpunit/phpunit": "^5.7",
+        "guzzle/plugin-mock": "^3.1",
+        "omnipay/dummy": "^2.1",
+        "omnipay/paymentexpress": "^2.1"
+    },
     "extra": {
         "branch-alias": {
             "dev-master": "2.x-dev"