diff --git a/GNUmakefile b/GNUmakefile
index 82f865b4..ca31d7fb 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -349,7 +349,7 @@ mdbx_example: mdbx.h example/example-mdbx.c libmdbx.$(SO_SUFFIX)
 build-test: all mdbx_example mdbx_test
 
 define test-rule
-$(patsubst %.cc,%.o,$(1)): $(1) $(TEST_INC) mdbx.h $(lastword $(MAKEFILE_LIST))
+$(patsubst %.cc,%.o,$(1)): $(1) $(TEST_INC) $(HEADERS) $(lastword $(MAKEFILE_LIST))
 	@echo '  CC $$@'
 	$(QUIET)$$(CXX) $$(CXXFLAGS) $$(MDBX_BUILD_OPTIONS) -c $(1) -o $$@
 
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index d97b78e1..82858066 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -1,7 +1,7 @@
 enable_language(CXX)
 include(../cmake/compiler.cmake)
 
-add_executable(mdbx_test
+set(LIBMDBX_TEST_SOURCES
   base.h
   cases.cc
   chrono.cc
@@ -30,6 +30,12 @@ add_executable(mdbx_test
   nested.cc
   )
 
+if(NOT MDBX_BUILD_CXX)
+  list(APPEND LIBMDBX_TEST_SOURCES "${MDBX_SOURCE_DIR}/mdbx.c++" ../mdbx.h++)
+endif()
+
+add_executable(mdbx_test ${LIBMDBX_TEST_SOURCES})
+
 if(MDBX_CXX_STANDARD)
   set_target_properties(mdbx_test PROPERTIES
     CXX_STANDARD ${MDBX_CXX_STANDARD} CXX_STANDARD_REQUIRED ON)
diff --git a/test/base.h b/test/base.h
index be8e05e3..790ffd0f 100644
--- a/test/base.h
+++ b/test/base.h
@@ -86,7 +86,7 @@
 #define MDBX_INTERNAL_FUNC
 #define MDBX_INTERNAL_VAR extern
 #define xMDBX_TOOLS /* Avoid using internal mdbx_assert() */
-#include "../mdbx.h"
+#include "../mdbx.h++"
 #include "../src/defs.h"
 #include "../src/osal.h"
 
diff --git a/test/test.cc b/test/test.cc
index cf50decb..f1494f8e 100644
--- a/test/test.cc
+++ b/test/test.cc
@@ -1058,10 +1058,8 @@ bool testcase::speculum_verify() {
     const auto S_key = iov2dataview(akey);
     const auto S_data = iov2dataview(avalue);
     if (it != speculum.cend()) {
-      mkey.iov_base = (void *)it->first.c_str();
-      mkey.iov_len = it->first.size();
-      mvalue.iov_base = (void *)it->second.c_str();
-      mvalue.iov_len = it->second.size();
+      mkey = it->first;
+      mvalue = it->second;
     }
     if (err == MDBX_SUCCESS && it != speculum.cend() && S_key == it->first &&
         S_data == it->second) {
diff --git a/test/test.h b/test/test.h
index cbd3d710..57b707c7 100644
--- a/test/test.h
+++ b/test/test.h
@@ -135,11 +135,7 @@ public:
 
 class testcase {
 protected:
-#if HAVE_cxx17_std_string_view
-  using data_view = std::string_view;
-#else
-  using data_view = std::string;
-#endif
+  using data_view = mdbx::slice;
   static inline data_view iov2dataview(const MDBX_val &v) {
     return (v.iov_base && v.iov_len)
                ? data_view(static_cast<const char *>(v.iov_base), v.iov_len)
@@ -149,7 +145,8 @@ protected:
     return iov2dataview(b->value);
   }
 
-  using Item = std::pair<std::string, std::string>;
+  using Item = std::pair<::mdbx::buffer<>, ::mdbx::buffer<>>;
+
   static MDBX_val dataview2iov(const data_view &v) {
     MDBX_val r;
     r.iov_base = (void *)v.data();
@@ -158,10 +155,13 @@ protected:
   }
   struct ItemCompare {
     const testcase *context;
-    ItemCompare(const testcase *owner) : context(owner) {}
+    ItemCompare(const testcase *owner) : context(owner) {
+      /* The context->txn_guard may be empty/null here */
+    }
 
     bool operator()(const Item &a, const Item &b) const {
       MDBX_val va = dataview2iov(a.first), vb = dataview2iov(b.first);
+      assert(context->txn_guard.get() != nullptr);
       int cmp = mdbx_cmp(context->txn_guard.get(), context->dbi, &va, &vb);
       if (cmp == 0 &&
           (context->config.params.table_flags & MDBX_DUPSORT) != 0) {