diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index bbf09ec..16a994a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -17,11 +17,11 @@ jobs:
   test:
     strategy:
       matrix:
-        os: 
+        os:
           - ubuntu
           - macos
           - windows
-        ruby: 
+        ruby:
           - 2.5
           - 2.6
           - 2.7
@@ -33,6 +33,15 @@ jobs:
           - jruby-head
           - truffleruby
           - truffleruby-head
+        exclude:
+          - os: macos
+            ruby: mingw
+          - os: macos
+            ruby: mswin
+          - os: ubuntu
+            ruby: mingw
+          - os: ubuntu
+            ruby: mswin
     runs-on: ${{ matrix.os }}-latest
     continue-on-error: ${{ endsWith(matrix.ruby, 'head') || matrix.ruby == 'debug' }}
     steps: