diff --git a/lib/govuk_schemas/validator.rb b/lib/govuk_schemas/validator.rb
index 01f5fbd..e75c242 100644
--- a/lib/govuk_schemas/validator.rb
+++ b/lib/govuk_schemas/validator.rb
@@ -1,11 +1,12 @@
 module GovukSchemas
   class Validator
-    attr_reader :schema_name, :type, :payload
+    attr_reader :schema_name, :type
+    attr_accessor :payload
 
     def initialize(schema_name, type, payload)
       @schema_name = schema_name
       @type = type
-      @payload = payload
+      @payload = ensure_json(payload)
     end
 
     def valid?
@@ -27,14 +28,12 @@ def error_message
 
     def errors
       schema = Schema.find("#{type}_schema": schema_name)
-      validator = JSON::Validator.fully_validate(schema, payload.to_json)
+      validator = JSON::Validator.fully_validate(schema, payload)
       validator.map { |message| "- " + humanized_error(message) }.join("\n")
     end
 
     def formatted_payload
-      return payload if payload.is_a?(String)
-
-      JSON.pretty_generate(payload)
+      JSON.pretty_generate(JSON.parse(payload))
     end
 
     def humanized_error(message)
@@ -42,5 +41,11 @@ def humanized_error(message)
              .gsub(/in schema [0-9a-f\-]+/, "")
              .strip
     end
+
+    def ensure_json(payload)
+      return payload if payload.is_a?(String)
+
+      payload.to_json
+    end
   end
 end
diff --git a/spec/lib/validator_spec.rb b/spec/lib/validator_spec.rb
index 88ca00b..212f4f0 100644
--- a/spec/lib/validator_spec.rb
+++ b/spec/lib/validator_spec.rb
@@ -16,6 +16,13 @@
 
       expect(validator.valid?).to eq false
     end
+
+    it "handles the payload being passed as json" do
+      example = GovukSchemas::RandomExample.for_schema(publisher_schema: "placeholder").to_json
+      validator = described_class.new("placeholder", "publisher", example)
+
+      expect(validator.valid?).to eq true
+    end
   end
 
   describe "#error_message" do