diff --git a/include/bitcoin/system/define.hpp b/include/bitcoin/system/define.hpp
index a41beced11..c47c3acf5a 100644
--- a/include/bitcoin/system/define.hpp
+++ b/include/bitcoin/system/define.hpp
@@ -79,16 +79,4 @@ namespace bc = libbitcoin;
     namespace libbitcoin { constexpr auto with_arm = false; };
 #endif
 
-/// Workarounds for C++ noncompliance.
-/// ---------------------------------------------------------------------------
-
-/// C++17 (partial), see HAVE_EXECUTION.
-#if defined(HAVE_EXECUTION)
-    namespace libbitcoin { constexpr auto par_unseq = std::execution::par_unseq; }
-    namespace libbitcoin { constexpr auto seq = std::execution::seq; }
-#else
-    namespace libbitcoin { constexpr auto par_unseq = false; }
-    namespace libbitcoin { constexpr auto seq = false; }
-#endif
-
 #endif
diff --git a/include/bitcoin/system/have.hpp b/include/bitcoin/system/have.hpp
index ac4eccd62c..714e6fd6ac 100644
--- a/include/bitcoin/system/have.hpp
+++ b/include/bitcoin/system/have.hpp
@@ -204,16 +204,6 @@
     #endif
 #endif
 
-/// None on xcode.
-/// Requires link with -ltbb on gcc (v9).
-/// Experimental on clang (libcxx.llvm.org/Status/PSTL.html), requires:
-/// -fexperimental-library
-#if defined(HAVE_CPP17)
-    #if defined(HAVE_MSC)
-        #define HAVE_EXECUTION
-    #endif
-#endif
-
 /// These are manually configured here.
 /// ---------------------------------------------------------------------------
 
diff --git a/include/bitcoin/system/impl/hash/scrypt.ipp b/include/bitcoin/system/impl/hash/scrypt.ipp
index b18dd11de1..69b076ed20 100644
--- a/include/bitcoin/system/impl/hash/scrypt.ipp
+++ b/include/bitcoin/system/impl/hash/scrypt.ipp
@@ -45,9 +45,9 @@ CONSTEVAL auto& CLASS::
 concurrency() NOEXCEPT
 {
     if constexpr (Concurrent)
-        return bc::par_unseq;
+        return poolstl::execution::par;
     else
-        return bc::seq;
+        return poolstl::execution::seq;
 }
 
 // protected
@@ -499,7 +499,7 @@ CLASS::hash(data_array<Size>& out, const data_slice& password,
     //    B[i] = scryptROMix (r, B[i], N)
     // end for
     std::atomic_bool success{ true };
-    std_for_each(concurrency(), prblocks.begin(), prblocks.end(),
+    std::for_each(concurrency(), prblocks.begin(), prblocks.end(),
         [&](rblock_t& rblock) NOEXCEPT
         {
             success = success && romix(rblock);
diff --git a/include/bitcoin/system/preprocessor.hpp b/include/bitcoin/system/preprocessor.hpp
index ccade62d24..206c0d57ee 100644
--- a/include/bitcoin/system/preprocessor.hpp
+++ b/include/bitcoin/system/preprocessor.hpp
@@ -212,21 +212,12 @@
 #define FALLTHROUGH [[fallthrough]]
 
 /// C++17 (partial)
-#if defined(HAVE_EXECUTION)
-    #include <execution>
-    #define std_any_of(p, b, e, l) std::any_of((p), (b), (e), (l))
-    #define std_all_of(p, b, e, l) std::all_of((p), (b), (e), (l))
-    #define std_for_each(p, b, e, l) std::for_each((p), (b), (e), (l))
-    #define std_reduce(p, b, e, i, l) std::reduce((p), (b), (e), (i), (l))
-    #define std_transform(p, b, e, t, l) std::transform((p), (b), (e), (t), (l))
-#else
-    #include <bitcoin/system/execution.hpp>
-    #define std_any_of(p, b, e, l) std::any_of((b), (e), (l))
-    #define std_all_of(p, b, e, l) std::all_of((b), (e), (l))
-    #define std_for_each(p, b, e, l) std::for_each((b), (e), (l))
-    #define std_reduce(p, b, e, i, l) std::reduce((b), (e), (i), (l))
-    #define std_transform(p, b, e, t, l) std::transform((b), (e), (t), (l))
-#endif
+/// None on xcode.
+/// Requires link with -ltbb on gcc (v9).
+/// Experimental on clang (libcxx.llvm.org/Status/PSTL.html), requires:
+/// -fexperimental-library
+/// using poolstl, do not include <execution>.
+#include <bitcoin/system/execution.hpp>
 
 /// C++20 (partial)
 #if defined(HAVE_CONSTEVAL)
diff --git a/test/hacks.cpp b/test/hacks.cpp
index 4c521e17d6..1e90c47e1f 100644
--- a/test/hacks.cpp
+++ b/test/hacks.cpp
@@ -19,7 +19,7 @@
 #include "test.hpp"
 #include <utility>
 
-#if defined(DISABLED) && defined(HAVE_EXECUTION)
+#if defined(DISABLED)
 
 BOOST_AUTO_TEST_SUITE(skip_parser_tests)
 
@@ -274,7 +274,7 @@ BOOST_AUTO_TEST_CASE(skip_parser__skip_parse_concurrent_tx__factor__expected)
 
     for (size_t i = 0; i < factor; ++i)
     {
-        std::for_each(std::execution::par_unseq, jobs.begin(), jobs.end(),
+        std::for_each(poolstl::execution::par, jobs.begin(), jobs.end(),
             [&](const auto job)
             {
                 if (job)
@@ -299,7 +299,7 @@ BOOST_AUTO_TEST_CASE(skip_parser__skip_parse_concurrent_block__factor_txs__expec
     const auto expected1 = bitcoin_hash(tx_2);
     constexpr std_array<bool, factor> jobs{};
 
-    std::for_each(std::execution::par_unseq, jobs.begin(), jobs.end(),
+    std::for_each(poolstl::execution::par, jobs.begin(), jobs.end(),
         [&](const auto)
         {
             stream::in::copy input(tx_2);
diff --git a/test/hash/hash.hpp b/test/hash/hash.hpp
index f5a2f75379..7a3ffbf7e5 100644
--- a/test/hash/hash.hpp
+++ b/test/hash/hash.hpp
@@ -290,7 +290,7 @@ const auto sha_5 = data_chunk(1'000'000_size, to_byte('a'));
     constexpr auto alpha_count = 16'777'216_size;
     constexpr auto long_alpha_size = alpha_size * alpha_count;
     const auto alpha2 = to_array<alpha_size>("abcdefghbcdefghicdefghijdefghijkefghijklfghijklmghijklmnhijklmno");
-    const std_vector<long_hash> long_alpha(alpha2_count, alpha2);
+    const std_vector<long_hash> long_alpha(alpha_count, alpha2);
     const auto long_alpha_data = pointer_cast<const uint8_t>(long_alpha.front().data());
     const auto sha_6 = to_chunk(unsafe_array_cast<uint8_t, long_alpha_size>(long_alpha_data));
 #endif // !HAVE_SLOW_TESTS