diff --git a/CHANGELOG.md b/CHANGELOG.md
index a115d7e1f..e91cafde4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@ All notable changes to this project will be documented in this file. For info on
 
 ### Fixed
 
+- Fix using Rack::Session::Cookie with coder: Rack::Session::Cookie::Base64::{JSON,Zip}. ([#1666](https://github.com/rack/rack/issues/1666), [@jeremyevans](https://github.com/jeremyevans))
 - Avoid NoMethodError when accessing Rack::Session::Cookie without requiring delegate first. ([#1610](https://github.com/rack/rack/issues/1610), [@onigra](https://github.com/onigra))
 - Handle cookies with values that end in '=' ([#1645](https://github.com/rack/rack/pull/1645), [@lukaso](https://github.com/lukaso))
 
diff --git a/lib/rack/session/abstract/id.rb b/lib/rack/session/abstract/id.rb
index 638bd3b3b..bbc79668b 100644
--- a/lib/rack/session/abstract/id.rb
+++ b/lib/rack/session/abstract/id.rb
@@ -455,7 +455,12 @@ class SecureSessionHash < SessionHash
           def [](key)
             if key == "session_id"
               load_for_read!
-              id.public_id if id
+              case id
+              when SessionId
+                id.public_id
+              else
+                id
+              end
             else
               super
             end
diff --git a/test/spec_session_abstract_persisted_secure_secure_session_hash.rb b/test/spec_session_abstract_persisted_secure_secure_session_hash.rb
index 1a007eb4a..bbb8a900e 100644
--- a/test/spec_session_abstract_persisted_secure_secure_session_hash.rb
+++ b/test/spec_session_abstract_persisted_secure_secure_session_hash.rb
@@ -44,6 +44,15 @@ def store.load_session(req)
       @hash = Rack::Session::Abstract::PersistedSecure::SecureSessionHash.new(store, nil)
       assert_nil hash['session_id']
     end
+
+    it "returns value for non SessionId 'session_id' key" do
+      store = @store.new
+      def store.load_session(req)
+        ["id", {}]
+      end
+      @hash = Rack::Session::Abstract::PersistedSecure::SecureSessionHash.new(store, nil)
+      assert_equal "id", hash['session_id']
+    end
   end
 
   describe "#fetch" do