diff --git a/.github/compilers.json b/.github/compilers.json
index 950eeb1b2..925cd1019 100644
--- a/.github/compilers.json
+++ b/.github/compilers.json
@@ -81,22 +81,37 @@
   ],
   "msvc": [
     {
-      "version": "14.34",
+      "version": "14.44",
       "cxxstd": "20",
       "latest_cxxstd": "20",
       "runs_on": "windows-2022",
-      "b2_toolset": "msvc-14.3",
+      "b2_toolset": "msvc-14.4",
       "generator": "Visual Studio 17 2022",
       "is_earliest": true
     },
+    {
+      "version": "14.51",
+      "cxxstd": "20",
+      "latest_cxxstd": "20",
+      "runs_on": "windows-2025-vs2026",
+      "b2_toolset": "msvc-14.5",
+      "generator": "Ninja",
+      "is_latest": true
+    },
     {
       "version": "14.44",
       "cxxstd": "20",
       "latest_cxxstd": "20",
-      "runs_on": "windows-2022",
+      "runs_on": "windows-11-vs2026-arm",
       "b2_toolset": "msvc-14.4",
-      "generator": "Visual Studio 17 2022",
-      "is_latest": true
+      "msvc_toolset": "14.44"
+    },
+    {
+      "version": "14.51",
+      "cxxstd": "20",
+      "latest_cxxstd": "20",
+      "runs_on": "windows-11-vs2026-arm",
+      "b2_toolset": "msvc-14.5"
     }
   ],
   "mingw": [
diff --git a/.github/generate-matrix.py b/.github/generate-matrix.py
index 3bb01c99b..57b57993b 100644
--- a/.github/generate-matrix.py
+++ b/.github/generate-matrix.py
@@ -72,6 +72,8 @@ def make_entry(compiler_family, spec, **overrides):
         entry["shared"] = spec["shared"]
     if spec.get("vcpkg_triplet"):
         entry["vcpkg-triplet"] = spec["vcpkg_triplet"]
+    if spec.get("msvc_toolset"):
+        entry["msvc-toolset"] = spec["msvc_toolset"]
 
     # CMake builds only on earliest/latest compilers, unless explicitly disabled
     if spec.get("build_cmake") is False:
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 090fb467f..0cb3d7d56 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -85,6 +85,51 @@ jobs:
           check-latest: true
           trace-commands: true
 
+      # setup-cpp ignores the MSVC version and loads the image's default
+      # toolset, so without this check the matrix version is only a label.
+      # A side-by-side toolset (msvc-toolset) is pinned for B2 through a
+      # setup script, because B2 re-runs vcvarsall before building.
+      - name: Configure MSVC
+        id: msvc
+        if: matrix.compiler == 'msvc'
+        env:
+          MSVC_VERSION: ${{ matrix.version }}
+          MSVC_TOOLSET: ${{ matrix.msvc-toolset }}
+          B2_TOOLSET: ${{ matrix.b2-toolset }}
+        run: |
+          set -euo pipefail
+          # Not PROCESSOR_ARCHITECTURE: on ARM64 runners this bash step
+          # does not see ARM64 there, and picked the x64 toolset.
+          case "$RUNNER_ARCH" in
+            ARM64) arch=arm64; bin=HostARM64/ARM64; target=ARM64 ;;
+            X64)   arch=amd64; bin=Hostx64/x64;     target=x64 ;;
+            *)     echo "::error::Unsupported runner architecture: $RUNNER_ARCH"; exit 1 ;;
+          esac
+          check="$RUNNER_TEMP/msvc-banner.bat"
+          if [ -n "$MSVC_TOOLSET" ]; then
+            setup="$RUNNER_TEMP/vcvars-$MSVC_TOOLSET.bat"
+            printf '@call "%sAuxiliary\\Build\\vcvarsall.bat" %%* -vcvars_ver=%s\r\n' \
+              "$VCINSTALLDIR" "$MSVC_TOOLSET" > "$setup"
+            tools=( "$(cygpath -m "$VCINSTALLDIR")Tools/MSVC/$MSVC_TOOLSET."* )
+            cl="${tools[-1]}/bin/$bin/cl.exe"
+            test -f "$cl"
+            user_config="$RUNNER_TEMP/user-config.jam"
+            echo "using msvc : ${B2_TOOLSET#msvc-} : \"$cl\" : <setup>\"$(cygpath -m "$setup")\" ;" \
+              > "$user_config"
+            cat "$user_config"
+            echo "user-config=$(cygpath -m "$user_config")" >> "$GITHUB_OUTPUT"
+            printf '@call "%s" %s >nul\r\n@cl\r\n' "$(cygpath -w "$setup")" "$arch" > "$check"
+          else
+            printf '@cl\r\n' > "$check"
+          fi
+          out=$(cmd //c "$(cygpath -w "$check")" 2>&1 || true)
+          banner=$(printf '%s\n' "$out" | tr -d '\r' | grep -m1 'Compiler Version' || true)
+          echo "$banner"
+          case "$banner" in
+            *"Version 19.${MSVC_VERSION#14.}."*" for $target") ;;
+            *) echo "::error::Expected MSVC $MSVC_VERSION for $target, got: $banner"; exit 1 ;;
+          esac
+
       - name: Install packages
         uses: alandefreitas/cpp-actions/package-install@v1.9.0
         id: package-install
@@ -170,6 +215,7 @@ jobs:
           source-dir: boost-root
           modules: capy
           toolset: ${{ matrix.b2-toolset }}
+          user-config: ${{ steps.msvc.outputs.user-config }}
           build-variant: ${{ (matrix.compiler == 'msvc' && 'debug,release') || matrix.build-type }}
           cxx: ${{ matrix.cxx || steps.setup-cpp.outputs.cxx || '' }}
           cxxstd: ${{ matrix.cxxstd }}