diff --git a/.github/workflows/ci_sh_def.yml b/.github/workflows/ci_sh_def.yml
index 39cd36d70..610877f41 100644
--- a/.github/workflows/ci_sh_def.yml
+++ b/.github/workflows/ci_sh_def.yml
@@ -887,32 +887,85 @@ jobs:
       run: cmake --build build -t check
 
   mingw:
+    name: "🐍 3 • windows-latest • ${{ matrix.sys }}"
     runs-on: windows-latest
     defaults:
       run:
         shell: msys2 {0}
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - { sys: mingw64, env: x86_64 }
+          - { sys: mingw32, env: i686 }
     steps:
     - uses: msys2/setup-msys2@v2
       with:
+        msystem: ${{matrix.sys}}
         install: >-
-          mingw-w64-x86_64-gcc
-          mingw-w64-x86_64-python-pip
-          mingw-w64-x86_64-cmake
-          mingw-w64-x86_64-make
-          mingw-w64-x86_64-python-pytest
-          mingw-w64-x86_64-eigen3
-          mingw-w64-x86_64-boost
-          mingw-w64-x86_64-catch
+          git
+          mingw-w64-${{matrix.env}}-gcc
+          mingw-w64-${{matrix.env}}-python-pip
+          mingw-w64-${{matrix.env}}-python-numpy
+          mingw-w64-${{matrix.env}}-python-scipy
+          mingw-w64-${{matrix.env}}-cmake
+          mingw-w64-${{matrix.env}}-make
+          mingw-w64-${{matrix.env}}-python-pytest
+          mingw-w64-${{matrix.env}}-eigen3
+          mingw-w64-${{matrix.env}}-boost
+          mingw-w64-${{matrix.env}}-catch
 
-    - uses: actions/checkout@v1
+    - uses: actions/checkout@v2
 
-    - name: Configure
+    - name: Configure C++11
       # LTO leads to many undefined reference like
       # `pybind11::detail::function_call::function_call(pybind11::detail::function_call&&)
-      run: cmake -G "MinGW Makefiles" -S . -B build -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
+      run: cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=11 -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT" -S . -B build
 
-    - name: Build
+    - name: Build C++11
       run: cmake --build build -j 2
 
-    - name: Python tests
-      run: cmake --build build --target pytest
+    - name: Python tests C++11
+      run: cmake --build build --target pytest -j 2
+
+    - name: C++11 tests
+      run: cmake --build build --target cpptest -j 2
+
+    - name: Interface test C++11
+      run: cmake --build build --target test_cmake_build
+
+    - name: Clean directory
+      run: git clean -fdx
+
+    - name: Configure C++14
+      run: cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=14 -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT" -S . -B build2
+
+    - name: Build C++14
+      run: cmake --build build2 -j 2
+
+    - name: Python tests C++14
+      run: cmake --build build2 --target pytest -j 2
+
+    - name: C++14 tests
+      run: cmake --build build2 --target cpptest -j 2
+
+    - name: Interface test C++14
+      run: cmake --build build2 --target test_cmake_build
+
+    - name: Clean directory
+      run: git clean -fdx
+
+    - name: Configure C++17
+      run: cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=17 -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT" -S . -B build3
+
+    - name: Build C++17
+      run: cmake --build build3 -j 2
+
+    - name: Python tests C++17
+      run: cmake --build build3 --target pytest -j 2
+
+    - name: C++17 tests
+      run: cmake --build build3 --target cpptest -j 2
+
+    - name: Interface test C++17
+      run: cmake --build build3 --target test_cmake_build
diff --git a/.github/workflows/ci_sh_def.yml.patch b/.github/workflows/ci_sh_def.yml.patch
index 83aeaa60c..c7bce62dd 100644
--- a/.github/workflows/ci_sh_def.yml.patch
+++ b/.github/workflows/ci_sh_def.yml.patch
@@ -1,5 +1,5 @@
---- ci.yml	2021-08-14 07:51:13.991347947 -0700
-+++ ci_sh_def.yml	2021-08-14 08:36:43.163463393 -0700
+--- ci.yml	2021-08-26 14:44:05.472874691 -0700
++++ ci_sh_def.yml	2021-08-26 15:02:18.318618529 -0700
 @@ -1,4 +1,16 @@
 -name: CI-SH-AVL
 +# PLEASE KEEP THIS GROUP OF FILES IN SYNC AT ALL TIMES:
@@ -140,12 +140,30 @@
  
      steps:
      - uses: actions/checkout@v2
-@@ -884,7 +909,7 @@
-     - name: Configure
+@@ -895,7 +920,7 @@
+     - name: Configure C++11
        # LTO leads to many undefined reference like
        # `pybind11::detail::function_call::function_call(pybind11::detail::function_call&&)
--      run: cmake -G "MinGW Makefiles" -S . -B build
-+      run: cmake -G "MinGW Makefiles" -S . -B build -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT"
+-      run: cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=11 -S . -B build
++      run: cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=11 -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT" -S . -B build
  
-     - name: Build
+     - name: Build C++11
        run: cmake --build build -j 2
+@@ -913,7 +938,7 @@
+       run: git clean -fdx
+ 
+     - name: Configure C++14
+-      run: cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=14 -S . -B build2
++      run: cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=14 -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT" -S . -B build2
+ 
+     - name: Build C++14
+       run: cmake --build build2 -j 2
+@@ -931,7 +956,7 @@
+       run: git clean -fdx
+ 
+     - name: Configure C++17
+-      run: cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=17 -S . -B build3
++      run: cmake -G "MinGW Makefiles" -DCMAKE_CXX_STANDARD=17 -DCMAKE_CXX_FLAGS="-DPYBIND11_USE_SMART_HOLDER_AS_DEFAULT" -S . -B build3
+ 
+     - name: Build C++17
+       run: cmake --build build3 -j 2