diff --git a/.github/workflows/protocol.yml b/.github/workflows/protocol.yml
index fb9c3b204..666ab4375 100644
--- a/.github/workflows/protocol.yml
+++ b/.github/workflows/protocol.yml
@@ -6,6 +6,9 @@ on:
   pull_request:
     branches: [ master ]
 
+permissions:
+  contents: read
+
 jobs:
   ruby-versions:
     uses: ruby/actions/.github/workflows/ruby_versions.yml@master
diff --git a/.github/workflows/ruby-macos.yaml b/.github/workflows/ruby-macos.yaml
index 6e4d6bc06..e48eeb2cf 100644
--- a/.github/workflows/ruby-macos.yaml
+++ b/.github/workflows/ruby-macos.yaml
@@ -6,6 +6,9 @@ on:
   pull_request:
     branches: [ master ]
 
+permissions:
+  contents: read
+
 jobs:
   ruby-versions:
     uses: ruby/actions/.github/workflows/ruby_versions.yml@master
diff --git a/.github/workflows/ruby.yml b/.github/workflows/ruby.yml
index 2666dc282..f53c61da7 100644
--- a/.github/workflows/ruby.yml
+++ b/.github/workflows/ruby.yml
@@ -6,6 +6,9 @@ on:
   pull_request:
     branches: [ master ]
 
+permissions:
+  contents: read
+
 jobs:
   ruby-versions:
     uses: ruby/actions/.github/workflows/ruby_versions.yml@master
diff --git a/.github/workflows/test_test.yml b/.github/workflows/test_test.yml
index f4339bf35..72e31affb 100644
--- a/.github/workflows/test_test.yml
+++ b/.github/workflows/test_test.yml
@@ -6,6 +6,9 @@ on:
   pull_request:
     branches: [ master ]
 
+permissions:
+  contents: read
+
 jobs:
   ruby-versions:
     uses: ruby/actions/.github/workflows/ruby_versions.yml@master
diff --git a/.github/workflows/truffleruby.yml b/.github/workflows/truffleruby.yml
index 2d05d2ce7..a3ec885bd 100644
--- a/.github/workflows/truffleruby.yml
+++ b/.github/workflows/truffleruby.yml
@@ -6,6 +6,9 @@ on:
   pull_request:
     branches: [ master ]
 
+permissions:
+  contents: read
+
 jobs:
   truffleruby:
     runs-on: ubuntu-latest