diff --git a/lib/two_factor_authentication/models/two_factor_authenticatable.rb b/lib/two_factor_authentication/models/two_factor_authenticatable.rb
index d55a851..410055a 100644
--- a/lib/two_factor_authentication/models/two_factor_authenticatable.rb
+++ b/lib/two_factor_authentication/models/two_factor_authenticatable.rb
@@ -32,7 +32,7 @@ module Devise
         end
 
         def otp_code(time = Time.now)
-          ROTP::TOTP.new(self.otp_column).at(time)
+          ROTP::TOTP.new(self.otp_column).at(time, true)
         end
 
         def provisioning_uri(account = nil, options = {})
diff --git a/spec/lib/two_factor_authentication/models/two_factor_authenticatable_spec.rb b/spec/lib/two_factor_authentication/models/two_factor_authenticatable_spec.rb
index efa8e37..014a432 100644
--- a/spec/lib/two_factor_authentication/models/two_factor_authenticatable_spec.rb
+++ b/spec/lib/two_factor_authentication/models/two_factor_authenticatable_spec.rb
@@ -25,7 +25,15 @@ describe Devise::Models::TwoFactorAuthenticatable, '#otp_code' do
       let(:time) { 1392852756 }
 
       it "should return a known result" do
-        expect(subject).to eq(562202)
+        expect(subject).to eq('562202')
+      end
+    end
+
+    context "with a known time yielding a result with less than 6 digits" do
+      let(:time) { 1393065856 }
+
+      it "should return a known result padded with zeroes" do
+        expect(subject).to eq('007672')
       end
     end
   end