diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 3728974..866d109 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -17,6 +17,7 @@ jobs:
           - '3.2'
           - '3.3'
           - '3.4'
+          - '4.0'
       fail-fast: false
 
     steps:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5328884..bbd3211 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## [Unreleased]
+
+- Support Ruby 4.0
+
 ## [1.2.1] - 2026-06-10
 
 - Require `oauth2 >= 2.0.22` to address GHSA-pp92-crg2-gfv9, where a
diff --git a/Gemfile.lock b/Gemfile.lock
index 3a836c7..8b9a7b3 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -13,6 +13,7 @@ PATH
   specs:
     booqable (1.2.1)
       addressable (~> 2.8)
+      cgi (~> 0.5)
       faraday (~> 2.13)
       faraday-retry (~> 2.3)
       jwt (~> 3.1)
@@ -44,6 +45,7 @@ GEM
     base64 (0.3.0)
     benchmark (0.5.0)
     bigdecimal (4.1.2)
+    cgi (0.5.2)
     concurrent-ruby (1.3.7)
     connection_pool (3.0.2)
     crack (1.0.1)
diff --git a/booqable.gemspec b/booqable.gemspec
index 513d49c..55e35d2 100644
--- a/booqable.gemspec
+++ b/booqable.gemspec
@@ -36,6 +36,7 @@ Gem::Specification.new do |spec|
   spec.add_dependency "addressable", "~> 2.8"
   spec.add_dependency "oauth2", "~> 2.0", ">= 2.0.22"
   spec.add_dependency "jwt", "~> 3.1"
+  spec.add_dependency "cgi", "~> 0.5"
 
   # For more information and examples about making a new gem, check out our
   # guide at: https://bundler.io/guides/creating_gem.html
diff --git a/lib/booqable.rb b/lib/booqable.rb
index 2658774..67f03a7 100644
--- a/lib/booqable.rb
+++ b/lib/booqable.rb
@@ -6,6 +6,7 @@
 require "json"
 require "sawyer"
 require "sawyer/link_parsers/simple"
+require "cgi"
 
 # Internal
 require_relative "booqable/version"