diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c98ffbf..86e2d6b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -14,12 +14,12 @@ jobs:
       fail-fast: false
       matrix:
         ruby-version: [2.6, 2.7, "3.0", 3.1, 3.2]
-        bundler-version: [2.4.19, 2.4.22, 2.5.7]
+        bundler-version: [2.4.19, 2.4.22, 2.5.9]
         exclude:
           - ruby-version: 2.6
-            bundler-version: 2.5.7
+            bundler-version: 2.5.9
           - ruby-version: 2.7
-            bundler-version: 2.5.7
+            bundler-version: 2.5.9
     env:
       BUNDLER_VERSION: ${{ matrix.bundler-version }}
       BUNDLE_LOCKFILE: active
diff --git a/Gemfile.lock b/Gemfile.lock
index 5458579..750b3a6 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -102,4 +102,4 @@ DEPENDENCIES
   stringio (~> 3.1)
 
 BUNDLED WITH
-   2.5.7
+   2.5.9
diff --git a/Gemfile.ruby-2.6.lock b/Gemfile.ruby-2.6.lock
index 4d00204..177d579 100644
--- a/Gemfile.ruby-2.6.lock
+++ b/Gemfile.ruby-2.6.lock
@@ -50,4 +50,4 @@ DEPENDENCIES
   stringio (= 3.0.6)
 
 BUNDLED WITH
-   2.5.7
+   2.5.9