diff --git a/src/Data/OpenApi/Lens.hs b/src/Data/OpenApi/Lens.hs
index b8e23101..1477ed80 100644
--- a/src/Data/OpenApi/Lens.hs
+++ b/src/Data/OpenApi/Lens.hs
@@ -101,6 +101,14 @@ instance At   Operation where at n = responses . at n
 
 instance HasType NamedSchema (Maybe OpenApiType) where type_ = schema.type_
 
+-- Type family instances for SecurityDefinitions type
+type instance Index SecurityDefinitions = Text
+type instance IxValue SecurityDefinitions = SecurityScheme
+
+-- Type-Class instances for SecurityDefinitions type
+instance Ixed SecurityDefinitions where ix n = (coerced :: Lens' SecurityDefinitions (Definitions SecurityScheme)). ix n
+instance At   SecurityDefinitions where at n = (coerced :: Lens' SecurityDefinitions (Definitions SecurityScheme)). at n
+
 -- OVERLAPPABLE instances
 
 instance