diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 7e94c7bd..3d5df82c 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -59,7 +59,7 @@ jobs:
         # To keep matrix size down, only test highest and lowest rubies. In
         # `.rubocop.yml`, set `TargetRubyVersion`, to the lowest ruby version
         # tested here.
-        ruby: ["2.6", "3.3"]
+        ruby: ["2.6", "3.4"]
         rails: ["5.2", "6.0", "6.1", "7.0", "7.1", "7.2", "8.0"]
         exclude:
           # rails 7 requires ruby >= 2.7.0
@@ -71,7 +71,7 @@ jobs:
             rails: "7.2"
           - ruby: "2.6"
             rails: "8.0"
-          - ruby: "3.3"
+          - ruby: "3.4"
             rails: "5.2"
     steps:
       - name: Checkout source
diff --git a/authlogic.gemspec b/authlogic.gemspec
index d0eb418c..b73212e4 100644
--- a/authlogic.gemspec
+++ b/authlogic.gemspec
@@ -29,11 +29,13 @@ require "authlogic/version"
   s.add_dependency "activerecord", [">= 5.2", "< 8.1"]
   s.add_dependency "activesupport", [">= 5.2", "< 8.1"]
   s.add_dependency "request_store", "~> 1.0"
+  s.add_development_dependency "base64"
   s.add_development_dependency "bcrypt", "~> 3.1"
   s.add_development_dependency "byebug", "~> 11.1.3"
   s.add_development_dependency "coveralls_reborn", "~> 0.28.0"
   s.add_development_dependency "minitest", "< 5.19.0" # See https://github.com/binarylogic/authlogic/issues/766
   s.add_development_dependency "minitest-reporters", "~> 1.3"
+  s.add_development_dependency "mutex_m"
   s.add_development_dependency "rake", "~> 13.0"
   s.add_development_dependency "rubocop", "~> 0.80.1"
   s.add_development_dependency "rubocop-performance", "~> 1.1"