diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index f5be324a..8c33461e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -205,7 +205,7 @@ jobs:
         run: ..\..\..\b2 --hash %ARGS%
         working-directory: ../boost-root/libs/regex/test
   windows_msvc_14_0:
-    runs-on: windows-latest
+    runs-on: windows-2019
     defaults:
       run:
         shell: cmd
@@ -252,7 +252,7 @@ jobs:
         run: ..\..\..\b2 --hash %ARGS%
         working-directory: ../boost-root/libs/regex/test
   windows_msvc_14_2:
-    runs-on: windows-latest
+    runs-on: windows-2019
     defaults:
       run:
         shell: cmd
@@ -298,6 +298,53 @@ jobs:
       - name: Test
         run: ..\..\..\b2 --hash %ARGS%
         working-directory: ../boost-root/libs/regex/test
+  windows_msvc_14_3:
+    runs-on: windows-2022
+    defaults:
+      run:
+        shell: cmd
+    env:
+      ARGS: toolset=${{ matrix.toolset }} address-model=64 cxxstd=${{ matrix.standard }}
+    strategy:
+      fail-fast: false
+      matrix:
+        toolset: [ msvc-14.3 ]
+        standard: [ 14, 17, 20, latest ]
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: '0'
+      - uses: mstachniuk/ci-skip@v1
+        with:
+          commit-filter: '[skip ci];[ci skip];[CI SKIP];[SKIP CI];***CI SKIP***;***SKIP CI***;[apple];[Apple];[APPLE];[linux];[Linux];[LINUX]'
+          commit-filter-separator: ';'
+          fail-fast: true
+      - name: Checkout main boost
+        run: git clone -b develop --depth 1 https://github.com/boostorg/boost.git ../boost-root
+      - name: Update tools/boostdep
+        run: git submodule update --init tools/boostdep
+        working-directory: ../boost-root
+      - name: Copy files
+        run: xcopy /s /e /q %GITHUB_WORKSPACE% libs\regex
+        working-directory: ../boost-root
+      - name: Install deps
+        run: python tools/boostdep/depinst/depinst.py -I example -g "--jobs 3" regex
+        working-directory: ../boost-root
+      - name: Bootstrap
+        run: bootstrap
+        working-directory: ../boost-root
+      - name: Generate headers
+        run: b2 headers
+        working-directory: ../boost-root
+      - name: Config info install
+        run: ..\..\..\b2 config_info_travis_install %ARGS%
+        working-directory: ../boost-root/libs/config/test
+      - name: Config info
+        run: config_info_travis
+        working-directory: ../boost-root/libs/config/test
+      - name: Test
+        run: ..\..\..\b2 --hash %ARGS%
+        working-directory: ../boost-root/libs/regex/test
   ubuntu-cmake-install:
     runs-on: ubuntu-20.04
     strategy:
diff --git a/include/boost/regex/v5/mem_block_cache.hpp b/include/boost/regex/v5/mem_block_cache.hpp
index eb3ec776..3e1216d0 100644
--- a/include/boost/regex/v5/mem_block_cache.hpp
+++ b/include/boost/regex/v5/mem_block_cache.hpp
@@ -34,6 +34,7 @@
 namespace boost{
 namespace BOOST_REGEX_DETAIL_NS{
 
+#if BOOST_REGEX_MAX_CACHE_BLOCKS != 0
 #ifdef BOOST_REGEX_MEM_BLOCK_CACHE_LOCK_FREE /* lock free implementation */
 struct mem_block_cache
 {
@@ -138,6 +139,7 @@ struct mem_block_cache
    }
 };
 #endif
+#endif
 
 #if BOOST_REGEX_MAX_CACHE_BLOCKS == 0
 
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index 87bc1607..edbe190a 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -94,6 +94,15 @@ test-suite regex
         <define>TEST_THREADS
         : regex_regress_threaded ]
 
+      [ run regress/$(R_SOURCE) ../build//boost_regex
+                                ../../thread/build//boost_thread ../build//icu_options
+        : # command line
+        : # input files
+        : # requirements
+        <define>TEST_THREADS
+        <define>BOOST_REGEX_MAX_CACHE_BLOCKS=0
+        : regex_regress_threaded_no_cache ]
+
       [ regex-test posix_api_check : c_compiler_checks/posix_api_check.c ]
 
       [ compile c_compiler_checks/wide_posix_api_check.c 
diff --git a/test/regress/test_sets.cpp b/test/regress/test_sets.cpp
index 3cd7a520..32f10450 100644
--- a/test/regress/test_sets.cpp
+++ b/test/regress/test_sets.cpp
@@ -170,19 +170,19 @@ void test_sets2()
    TEST_INVALID_REGEX("[[.NUL.]", perl);
    TEST_INVALID_REGEX("[[:<:]z]", perl);
    TEST_INVALID_REGEX("[a[:>:]]", perl);
-   TEST_REGEX_SEARCH("[[.A.]]", boost::regex::extended|icase, "A", match_default, make_array(0, 1, -2, -2));
-   TEST_REGEX_SEARCH("[[.A.]]", boost::regex::extended|icase, "a", match_default, make_array(0, 1, -2, -2));
-   TEST_REGEX_SEARCH("[[.A.]-b]+", boost::regex::extended|icase, "AaBb", match_default, make_array(0, 4, -2, -2));
-   TEST_REGEX_SEARCH("[A-[.b.]]+", boost::regex::extended|icase, "AaBb", match_default, make_array(0, 4, -2, -2));
-   TEST_REGEX_SEARCH("[[.a.]-B]+", boost::regex::extended|icase, "AaBb", match_default, make_array(0, 4, -2, -2));
-   TEST_REGEX_SEARCH("[a-[.B.]]+", boost::regex::extended|icase, "AaBb", match_default, make_array(0, 4, -2, -2));
-   TEST_REGEX_SEARCH("[\x61]", boost::regex::extended, "a", match_default, make_array(0, 1, -2, -2));
-   TEST_REGEX_SEARCH("[\x61-c]+", boost::regex::extended, "abcd", match_default, make_array(0, 3, -2, -2));
-   TEST_REGEX_SEARCH("[a-\x63]+", boost::regex::extended, "abcd", match_default, make_array(0, 3, -2, -2));
-   TEST_REGEX_SEARCH("[[.a.]-c]+", boost::regex::extended, "abcd", match_default, make_array(0, 3, -2, -2));
-   TEST_REGEX_SEARCH("[a-[.c.]]+", boost::regex::extended, "abcd", match_default, make_array(0, 3, -2, -2));
-   TEST_INVALID_REGEX("[[:alpha:]-a]", boost::regex::extended);
-   TEST_INVALID_REGEX("[a-[:alpha:]]", boost::regex::extended);
+   TEST_REGEX_SEARCH("[[.A.]]", extended|icase, "A", match_default, make_array(0, 1, -2, -2));
+   TEST_REGEX_SEARCH("[[.A.]]", extended|icase, "a", match_default, make_array(0, 1, -2, -2));
+   TEST_REGEX_SEARCH("[[.A.]-b]+", extended|icase, "AaBb", match_default, make_array(0, 4, -2, -2));
+   TEST_REGEX_SEARCH("[A-[.b.]]+", extended|icase, "AaBb", match_default, make_array(0, 4, -2, -2));
+   TEST_REGEX_SEARCH("[[.a.]-B]+", extended|icase, "AaBb", match_default, make_array(0, 4, -2, -2));
+   TEST_REGEX_SEARCH("[a-[.B.]]+", extended|icase, "AaBb", match_default, make_array(0, 4, -2, -2));
+   TEST_REGEX_SEARCH("[\x61]", extended, "a", match_default, make_array(0, 1, -2, -2));
+   TEST_REGEX_SEARCH("[\x61-c]+", extended, "abcd", match_default, make_array(0, 3, -2, -2));
+   TEST_REGEX_SEARCH("[a-\x63]+", extended, "abcd", match_default, make_array(0, 3, -2, -2));
+   TEST_REGEX_SEARCH("[[.a.]-c]+", extended, "abcd", match_default, make_array(0, 3, -2, -2));
+   TEST_REGEX_SEARCH("[a-[.c.]]+", extended, "abcd", match_default, make_array(0, 3, -2, -2));
+   TEST_INVALID_REGEX("[[:alpha:]-a]", extended);
+   TEST_INVALID_REGEX("[a-[:alpha:]]", extended);
    TEST_REGEX_SEARCH("[[.ae.]]", basic, "ae", match_default, make_array(0, 2, -2, -2));
    TEST_REGEX_SEARCH("[[.ae.]]", basic, "aE", match_default, make_array(-2, -2));
    TEST_REGEX_SEARCH("[[.AE.]]", basic, "AE", match_default, make_array(0, 2, -2, -2));