diff --git a/_config/config.yml b/_config/config.yml
index acd3168..301d2c6 100644
--- a/_config/config.yml
+++ b/_config/config.yml
@@ -7,18 +7,18 @@ SilverStripe\Core\Injector\Injector:
   RedirectUrlDataSource:
     class: Heyday\SilverStripeRedirects\Source\DataSource\DataListDataSource
     constructor:
-      0: %$RedirectUrlDataList
-      1: %$Heyday\SilverStripeRedirects\Source\Transformer\RedirectUrlTransformer
+      0: '%$RedirectUrlDataList'
+      1: '%$Heyday\SilverStripeRedirects\Source\Transformer\RedirectUrlTransformer'
 
   CachedRedirectUrlDataSource:
     class: Heyday\SilverStripeRedirects\Source\DataSource\CachedDataSource
     constructor:
-      0: %$RedirectUrlDataSource
-      1: %$RedirectsCache
+      0: '%$RedirectUrlDataSource'
+      1: '%$RedirectsCache'
 
   Heyday\SilverStripeRedirects\Code\RedirectUrl:
     properties:
-      dataSource: %$CachedRedirectUrlDataSource
+      dataSource: '%$CachedRedirectUrlDataSource'
 
   RedirectUrlDataList:
     class: SilverStripe\ORM\DataList
@@ -27,13 +27,13 @@ SilverStripe\Core\Injector\Injector:
 
   Heyday\SilverStripeRedirects\Source\Redirector:
     constructor:
-      0: %$CachedRedirectUrlDataSource
+      0: '%$CachedRedirectUrlDataSource'
 
   Heyday\SilverStripeRedirects\Source\RequestFilter:
     constructor:
-      0: %$Heyday\SilverStripeRedirects\Source\Redirector
+      0: '%$Heyday\SilverStripeRedirects\Source\Redirector'
 
   SilverStripe\Control\RequestProcessor:
     properties:
       filters:
-        - '%$Heyday\SilverStripeRedirects\Source\RequestFilter'
\ No newline at end of file
+        - '%$Heyday\SilverStripeRedirects\Source\RequestFilter'