diff --git a/test/common/modsecurity_test.cc b/test/common/modsecurity_test.cc
index 227571919b..0f769054e8 100644
--- a/test/common/modsecurity_test.cc
+++ b/test/common/modsecurity_test.cc
@@ -93,13 +93,13 @@ bool ModSecurityTest<T>::load_test_json(const std::string &file) {
 
 
 template <class T>
-std::pair<std::string, std::vector<T *>>*
+void
 ModSecurityTest<T>::load_tests(const std::string &path) {
     DIR *dir;
     struct dirent *ent;
     struct stat buffer;
 
-    if ((dir = opendir(path.c_str())) == NULL) {
+    if ((dir = opendir(path.c_str())) == nullptr) {
         /* if target is a file, use it as a single test. */
         if (stat(path.c_str(), &buffer) == 0) {
             if (load_test_json(path) == false) {
@@ -107,10 +107,10 @@ ModSecurityTest<T>::load_tests(const std::string &path) {
                 std::cout << std::endl;
             }
         }
-        return NULL;
+        return;
     }
 
-    while ((ent = readdir(dir)) != NULL) {
+    while ((ent = readdir(dir)) != nullptr) {
         std::string filename = ent->d_name;
         std::string json = ".json";
         if (filename.size() < json.size()
@@ -123,16 +123,15 @@ ModSecurityTest<T>::load_tests(const std::string &path) {
         }
     }
     closedir(dir);
-
-    return NULL;
 }
 
 
 template <class T>
-std::pair<std::string, std::vector<T *>>* ModSecurityTest<T>::load_tests() {
-    return load_tests(this->target);
+void ModSecurityTest<T>::load_tests() {
+    load_tests(this->target);
 }
 
+
 template <class T>
 void ModSecurityTest<T>::cmd_options(int argc, char **argv) {
     int i = 1;
@@ -144,6 +143,10 @@ void ModSecurityTest<T>::cmd_options(int argc, char **argv) {
         i++;
         m_count_all = true;
     }
+    if (argc > i && strcmp(argv[i], "mtstress") == 0) {
+        i++;
+        m_test_multithreaded = true;
+    }
     if (std::getenv("AUTOMAKE_TESTS")) {
         m_automake_output = true;
     }
diff --git a/test/common/modsecurity_test.h b/test/common/modsecurity_test.h
index 79a168f71c..8b55a16c62 100644
--- a/test/common/modsecurity_test.h
+++ b/test/common/modsecurity_test.h
@@ -34,12 +34,13 @@ template <class T> class ModSecurityTest :
     ModSecurityTest()
         : m_test_number(0),
         m_automake_output(false),
-        m_count_all(false) { }
+        m_count_all(false),
+        m_test_multithreaded(false) { }
 
     std::string header();
     void cmd_options(int, char **);
-    std::pair<std::string, std::vector<T *>>* load_tests();
-    std::pair<std::string, std::vector<T *>>* load_tests(const std::string &path);
+    void load_tests();
+    void load_tests(const std::string &path);
     bool load_test_json(const std::string &file);
 
     std::string target;
@@ -48,6 +49,7 @@ template <class T> class ModSecurityTest :
     int m_test_number;
     bool m_automake_output;
     bool m_count_all;
+    bool m_test_multithreaded;
 };
 
 }  // namespace modsecurity_test
diff --git a/test/unit/unit.cc b/test/unit/unit.cc
index 46013ec744..7b62e7f7e3 100644
--- a/test/unit/unit.cc
+++ b/test/unit/unit.cc
@@ -15,7 +15,9 @@
 
 #include <string.h>
 #include <cstring>
-
+#include <cassert>
+#include <thread>
+#include <array>
 #include <iostream>
 #include <ctime>
 #include <string>
@@ -38,6 +40,7 @@
 
 
 using modsecurity_test::UnitTest;
+using modsecurity_test::UnitTestResult;
 using modsecurity_test::ModSecurityTest;
 using modsecurity_test::ModSecurityTestResults;
 using modsecurity::actions::transformations::Transformation;
@@ -53,64 +56,149 @@ void print_help() {
 }
 
 
-void perform_unit_test(ModSecurityTest<UnitTest> *test, UnitTest *t,
-    ModSecurityTestResults<UnitTest>* res) {
-    std::string error;
+struct OperatorTest {
+    using ItemType = Operator;
+
+    static ItemType* init(const UnitTest &t) {
+        auto op = Operator::instantiate(t.name, t.param);
+        assert(op != nullptr);
+
+        std::string error;
+        op->init(t.filename, &error);
+
+        return op;
+    }
+
+    static UnitTestResult eval(ItemType &op, const UnitTest &t) {
+        return {op.evaluate(nullptr, nullptr, t.input, nullptr), {}};
+    }
+
+    static bool check(const UnitTestResult &result, const UnitTest &t) {
+        return result.ret != t.ret;
+    }
+};
+
+
+struct TransformationTest {
+    using ItemType = Transformation;
+
+    static ItemType* init(const UnitTest &t) {
+        auto tfn = Transformation::instantiate("t:" + t.name);
+        assert(tfn != nullptr);
+
+        return tfn;
+    }
+
+    static UnitTestResult eval(ItemType &tfn, const UnitTest &t) {
+        return {1, tfn.evaluate(t.input, nullptr)};
+    }
+
+    static bool check(const UnitTestResult &result, const UnitTest &t) {
+        return result.output != t.output;
+    }
+};
+
+
+template<typename TestType>
+UnitTestResult perform_unit_test_once(const UnitTest &t) {
+    std::unique_ptr<typename TestType::ItemType> item(TestType::init(t));
+    assert(item.get() != nullptr);
+
+    return TestType::eval(*item.get(), t);
+}
+
+
+template<typename TestType>
+UnitTestResult perform_unit_test_multithreaded(const UnitTest &t) {
+
+    constexpr auto NUM_THREADS = 50;
+    constexpr auto ITERATIONS = 5'000;
+
+    std::array<std::thread, NUM_THREADS> threads;
+    std::array<UnitTestResult, NUM_THREADS> results;
+
+    std::unique_ptr<typename TestType::ItemType> item(TestType::init(t));
+    assert(item.get() != nullptr);
+
+    for (auto i = 0; i != threads.size(); ++i)
+    {
+        auto &result = results[i];
+        threads[i] = std::thread(
+            [&item, &t, &result]()
+            {
+                for (auto j = 0; j != ITERATIONS; ++j)
+                    result = TestType::eval(*item.get(), t);
+            });
+    }
+
+    UnitTestResult ret;
+
+    for (auto i = 0; i != threads.size(); ++i)
+    {
+        threads[i].join();
+        if (TestType::check(results[i], t))
+            ret = results[i];   // error value, keep iterating to join all threads
+        else if(i == 0)
+            ret = results[i];   // initial value
+    }
+
+    return ret; // cppcheck-suppress uninitvar ; false positive, ret assigned at least once in previous loop
+}
+
+
+template<typename TestType>
+void perform_unit_test_helper(const ModSecurityTest<UnitTest> &test, UnitTest &t,
+    ModSecurityTestResults<UnitTest> &res) {
+
+    if (!test.m_test_multithreaded)
+        t.result = perform_unit_test_once<TestType>(t);
+    else
+        t.result = perform_unit_test_multithreaded<TestType>(t);
+
+    if (TestType::check(t.result, t)) {
+        res.push_back(&t);
+        if (test.m_automake_output) {
+            std::cout << "FAIL ";
+        }
+    } else if (test.m_automake_output) {
+        std::cout << "PASS ";
+    }
+}
+
+
+void perform_unit_test(const ModSecurityTest<UnitTest> &test, UnitTest &t,
+    ModSecurityTestResults<UnitTest> &res) {
     bool found = true;
 
-    if (test->m_automake_output) {
+    if (test.m_automake_output) {
         std::cout << ":test-result: ";
     }
 
-    if (t->resource.empty() == false) {
-        found = (std::find(resources.begin(), resources.end(), t->resource)
-            != resources.end());
+    if (t.resource.empty() == false) {
+        found = std::find(resources.begin(), resources.end(), t.resource)
+            != resources.end();
     }
 
     if (!found) {
-        t->skipped = true;
-        res->push_back(t);
-        if (test->m_automake_output) {
+        t.skipped = true;
+        res.push_back(&t);
+        if (test.m_automake_output) {
             std::cout << "SKIP ";
         }
     }
 
-    if (t->type == "op") {
-        Operator *op = Operator::instantiate(t->name, t->param);
-        op->init(t->filename, &error);
-        int ret = op->evaluate(NULL, NULL, t->input, NULL);
-        t->obtained = ret;
-        if (ret != t->ret) {
-            res->push_back(t);
-            if (test->m_automake_output) {
-                std::cout << "FAIL ";
-            }
-        } else if (test->m_automake_output) {
-            std::cout << "PASS ";
-        }
-        delete op;
-    } else if (t->type == "tfn") {
-        Transformation *tfn = Transformation::instantiate("t:" + t->name);
-        std::string ret = tfn->evaluate(t->input, NULL);
-        t->obtained = 1;
-        t->obtainedOutput = ret;
-        if (ret != t->output) {
-            res->push_back(t);
-            if (test->m_automake_output) {
-                std::cout << "FAIL ";
-            }
-        } else if (test->m_automake_output) {
-            std::cout << "PASS ";
-        }
-        delete tfn;
+    if (t.type == "op") {
+        perform_unit_test_helper<OperatorTest>(test, t, res);
+    } else if (t.type == "tfn") {
+        perform_unit_test_helper<TransformationTest>(test, t, res);
     } else {
-        std::cerr << "Failed. Test type is unknown: << " << t->type;
+        std::cerr << "Failed. Test type is unknown: << " << t.type;
         std::cerr << std::endl;
     }
 
-    if (test->m_automake_output) {
-        std::cout << t->name << " "
-            << modsecurity::utils::string::toHexIfNeeded(t->input)
+    if (test.m_automake_output) {
+        std::cout << t.name << " "
+            << modsecurity::utils::string::toHexIfNeeded(t.input)
             << std::endl;
     }
 }
@@ -151,17 +239,15 @@ int main(int argc, char **argv) {
         test.load_tests("test-cases/secrules-language-tests/transformations");
     }
 
-    for (std::pair<std::string, std::vector<UnitTest *> *> a : test) {
-        std::vector<UnitTest *> *tests = a.second;
-
+    for (auto& [filename, tests] : test) {
         total += tests->size();
-        for (UnitTest *t : *tests) {
+        for (auto t : *tests) {
             ModSecurityTestResults<UnitTest> r;
 
             if (!test.m_automake_output) {
-                std::cout << "  " << a.first << "...\t";
+                std::cout << "  " << filename << "...\t";
             }
-            perform_unit_test(&test, t, &r);
+            perform_unit_test(test, *t, r);
 
             if (!test.m_automake_output) {
                 int skp = 0;
@@ -191,7 +277,7 @@ int main(int argc, char **argv) {
         std::cout << "Total >> "  << total << std::endl;
     }
 
-    for (UnitTest *t : results) {
+    for (const auto t : results) {
         std::cout << t->print() << std::endl;
     }
 
@@ -216,8 +302,8 @@ int main(int argc, char **argv) {
     }
 
     for (auto a : test) {
-        auto *vec = a.second;
-        for(auto *t : *vec)
+        auto vec = a.second;
+        for(auto t : *vec)
             delete t;
         delete vec;
     }
diff --git a/test/unit/unit_test.cc b/test/unit/unit_test.cc
index d15533a3cc..dee4f1ae12 100644
--- a/test/unit/unit_test.cc
+++ b/test/unit/unit_test.cc
@@ -102,15 +102,15 @@ std::string UnitTest::print() {
     i << "  \"param\": \"" << this->param << "\"" << std::endl;
     i << "  \"output\": \"" << this->output << "\"" << std::endl;
     i << "}" << std::endl;
-    if (this->ret != this->obtained) {
+    if (this->ret != this->result.ret) {
         i << "Expecting: \"" << this->ret << "\" - returned: \"";
-        i << this->obtained << "\"" << std::endl;
+        i << this->result.ret << "\"" << std::endl;
     }
-    if (this->output != this->obtainedOutput) {
+    if (this->output != this->result.output) {
         i << "Expecting: \"";
         i << modsecurity::utils::string::toHexIfNeeded(this->output);
         i << "\" - returned: \"";
-        i << modsecurity::utils::string::toHexIfNeeded(this->obtainedOutput);
+        i << modsecurity::utils::string::toHexIfNeeded(this->result.output);
         i << "\"";
         i << std::endl;
     }
diff --git a/test/unit/unit_test.h b/test/unit/unit_test.h
index d200db5dbc..81d99d1424 100644
--- a/test/unit/unit_test.h
+++ b/test/unit/unit_test.h
@@ -25,6 +25,12 @@
 
 namespace modsecurity_test {
 
+class UnitTestResult {
+ public:
+    int ret;
+    std::string output;
+};
+
 class UnitTest {
  public:
     static UnitTest *from_yajl_node(const yajl_val &);
@@ -39,9 +45,8 @@ class UnitTest {
     std::string filename;
     std::string output;
     int ret;
-    int obtained;
     int skipped;
-    std::string obtainedOutput;
+    UnitTestResult result;
 };
 
 }  // namespace modsecurity_test