diff --git a/docs/types/mutations.rst b/docs/types/mutations.rst
index 543f39b4..f8c76f35 100644
--- a/docs/types/mutations.rst
+++ b/docs/types/mutations.rst
@@ -48,7 +48,11 @@ So, we can finish our schema like this:
     class MyMutations(graphene.ObjectType):
         create_person = CreatePerson.Field()
 
-    schema = graphene.Schema(mutation=MyMutations)
+    # We must define a query for our schema
+    class Query(graphene.ObjectType):
+        person = graphene.Field(Person)
+
+    schema = graphene.Schema(query=Query, mutation=MyMutations)
 
 Executing the Mutation
 ----------------------
diff --git a/graphene/types/schema.py b/graphene/types/schema.py
index 0b6e9dac..29ead4a7 100644
--- a/graphene/types/schema.py
+++ b/graphene/types/schema.py
@@ -381,7 +381,7 @@ class Schema:
     questions about the types through introspection.
 
     Args:
-        query (Optional[Type[ObjectType]]): Root query *ObjectType*. Describes entry point for fields to *read*
+        query (Type[ObjectType]): Root query *ObjectType*. Describes entry point for fields to *read*
             data in your Schema.
         mutation (Optional[Type[ObjectType]]): Root mutation *ObjectType*. Describes entry point for
             fields to *create, update or delete* data in your API.