diff --git a/lib/jwt/encode.rb b/lib/jwt/encode.rb
index bda51bbd..35ddba79 100644
--- a/lib/jwt/encode.rb
+++ b/lib/jwt/encode.rb
@@ -13,7 +13,7 @@ def initialize(options)
       @payload   = options[:payload]
       @key       = options[:key]
       @algorithm = options[:algorithm]
-      @headers   = options[:headers]
+      @headers   = options[:headers].each_with_object({}) { |(key, value), headers| headers[key.to_s] = value }
     end
 
     def segments
@@ -39,7 +39,8 @@ def encoded_header_and_payload
     end
 
     def encode_header
-      encode(@headers.merge(ALG_KEY => @algorithm))
+      @headers[ALG_KEY] = @algorithm
+      encode(@headers)
     end
 
     def encode_payload
diff --git a/spec/jwt_spec.rb b/spec/jwt_spec.rb
index 1592c731..0fd5e64b 100644
--- a/spec/jwt_spec.rb
+++ b/spec/jwt_spec.rb
@@ -399,5 +399,9 @@
       headers = JSON.parse(::JWT::Base64.url_decode(JWT.encode('Hello World', 'secret', 'HS256', { alg: 'HS123'}).split('.').first))
       expect(headers['alg']).to eq('HS256')
     end
+
+    it "should generate the same token" do
+      expect(JWT.encode('Hello World', 'secret', 'HS256', { alg: 'HS256'})).to eq JWT.encode('Hello World', 'secret', 'HS256')
+    end
   end
 end