diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 41806af..eae04a3 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -14,4 +14,9 @@
             <directory>./tests/</directory>
         </testsuite>
     </testsuites>
+    <filter>
+        <whitelist>
+            <directory suffix=".php">src/</directory>
+        </whitelist>
+    </filter>
 </phpunit>
diff --git a/src/stubs/phpunit.txt b/src/stubs/phpunit.txt
index d92a238..9f913e0 100644
--- a/src/stubs/phpunit.txt
+++ b/src/stubs/phpunit.txt
@@ -14,4 +14,9 @@
             <directory>./tests/</directory>
         </testsuite>
     </testsuites>
+    <filter>
+        <whitelist>
+            <directory suffix=".php">src/</directory>
+        </whitelist>
+    </filter>
 </phpunit>