diff --git a/composer.json b/composer.json
index d6022b7bb..e4b14df79 100644
--- a/composer.json
+++ b/composer.json
@@ -74,7 +74,10 @@
       "SilverStripe\\View\\": "src/View/",
       "SilverStripe\\View\\Tests\\": "tests/php/View/"
     },
-    "files": ["src/Core/Constants.php"],
+    "files": [
+      "src/Core/Constants.php",
+      "src/Dev/PhpUnitShim.php"
+    ],
     "classmap": ["tests/behat/features/bootstrap"]
   },
   "include-path": [
diff --git a/src/Dev/PhpUnitShim.php b/src/Dev/PhpUnitShim.php
new file mode 100644
index 000000000..ef7921fe1
--- /dev/null
+++ b/src/Dev/PhpUnitShim.php
@@ -0,0 +1,14 @@
+<?php
+// Ensure this class can be autoloaded when installed without dev dependencies.
+// It's included by default through composer's autoloading.
+// class_exists() triggers PSR-4 autoloaders, which should discover if PHPUnit is installed.
+// TODO Factor out SapphireTest references from non-dev core code (avoid autoloading in the first place)
+namespace {
+
+    if (!class_exists('PHPUnit_Framework_TestCase')) {
+        class PHPUnit_Framework_TestCase
+        {
+        }
+    }
+
+}