diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 0154b99..7f2e0cb 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -8,7 +8,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: [2.3, 2.4, 2.5, 2.6, 2.7, '3.0', 3.1, 3.2, 3.3]
+        ruby: [2.3, 2.4, 2.5, 2.6, 2.7, '3.0', 3.1, 3.2, 3.3, 3.4]
         gemfile: ['rails42', 'rails50', 'rails51', 'rails52', 'rails60', 'rails61', 'rails70', 'rails71', 'rails72', 'rails80']
         exclude:
           - ruby: 2.3
@@ -95,6 +95,14 @@ jobs:
             gemfile: rails51
           - ruby: 3.3
             gemfile: rails52
+          - ruby: 3.4
+            gemfile: rails42
+          - ruby: 3.4
+            gemfile: rails50
+          - ruby: 3.4
+            gemfile: rails51
+          - ruby: 3.4
+            gemfile: rails52
 
     name: ruby ${{ matrix.ruby }}, ${{ matrix.gemfile }}
 
diff --git a/gemfiles/rails60.gemfile b/gemfiles/rails60.gemfile
index 3459c28..7832bf2 100644
--- a/gemfiles/rails60.gemfile
+++ b/gemfiles/rails60.gemfile
@@ -5,4 +5,9 @@ gem "sqlite3", "~> 1.4.0"
 
 gem "psych", "~> 3.3.0"
 
+if RUBY_VERSION >= "3.4"
+  gem "bigdecimal"
+  gem "mutex_m"
+end
+
 gemspec path: "../"
diff --git a/gemfiles/rails61.gemfile b/gemfiles/rails61.gemfile
index aea5504..5d34ead 100644
--- a/gemfiles/rails61.gemfile
+++ b/gemfiles/rails61.gemfile
@@ -3,4 +3,9 @@ source 'https://rubygems.org'
 gem "activerecord", "~> 6.1.0"
 gem "sqlite3", "~> 1.4.0"
 
+if RUBY_VERSION >= "3.4"
+  gem "bigdecimal"
+  gem "mutex_m"
+end
+
 gemspec path: "../"
diff --git a/gemfiles/rails70.gemfile b/gemfiles/rails70.gemfile
index 6819a5f..433902d 100644
--- a/gemfiles/rails70.gemfile
+++ b/gemfiles/rails70.gemfile
@@ -3,4 +3,9 @@ source 'https://rubygems.org'
 gem "activerecord", "~> 7.0.1"
 gem "sqlite3", "~> 1.4.0"
 
+if RUBY_VERSION >= "3.4"
+  gem "bigdecimal"
+  gem "mutex_m"
+end
+
 gemspec path: "../"