diff --git a/_config/processors.yml b/_config/processors.yml
index eac4898..7360db4 100644
--- a/_config/processors.yml
+++ b/_config/processors.yml
@@ -9,4 +9,4 @@ SilverStripe\Core\Injector\Injector:
   SilverStripe\Control\Director:
     properties:
       Middlewares:
-        TestSessionHTTPMiddleware: %$SilverStripe\TestSession\TestSessionHTTPMiddleware
+        TestSessionHTTPMiddleware: '%$SilverStripe\TestSession\TestSessionHTTPMiddleware'
diff --git a/_config/services.yml b/_config/services.yml
index 69c915f..7616ca4 100644
--- a/_config/services.yml
+++ b/_config/services.yml
@@ -5,4 +5,4 @@ SilverStripe\Core\Injector\Injector:
   SilverStripe\TestSession\TestSessionEnvironment:
     class: SilverStripe\TestSession\TestSessionEnvironment
   # shorthand alias for FQN
-  TestSessionEnvironment: %$SilverStripe\TestSession\TestSessionEnvironment
+  TestSessionEnvironment: '%$SilverStripe\TestSession\TestSessionEnvironment'