diff --git a/include/fintamath/core/CoreUtils.hpp b/include/fintamath/core/CoreUtils.hpp
index 81abe73e5..5d03f73ed 100644
--- a/include/fintamath/core/CoreUtils.hpp
+++ b/include/fintamath/core/CoreUtils.hpp
@@ -2,24 +2,27 @@
 
 #include <concepts>
 #include <functional>
-#include <ranges>
 
 namespace fintamath {
 
-namespace stdr = std::ranges;
-namespace stdv = std::views;
-
 template <typename From, typename To>
 concept ConvertibleToAndNotSameAs = std::convertible_to<From, To> && !std::same_as<From, To>;
 
-template <class T>
+template <typename T>
 concept TupleLike = requires {
   std::tuple_size<T>::value;
 };
 
-template <class T>
+template <typename T>
 concept Hashable = requires(const T &v) {
   std::hash<T>{}(v);
 };
 
+template <typename Number, typename Function>
+void repeat(const Number &num, Function &&func) {
+  for (Number i = 0; i < num; ++i) {
+    func();
+  }
+}
+
 }
diff --git a/include/fintamath/core/Hash.hpp b/include/fintamath/core/Hash.hpp
index a41c2d970..f30824e02 100644
--- a/include/fintamath/core/Hash.hpp
+++ b/include/fintamath/core/Hash.hpp
@@ -7,10 +7,10 @@
 
 namespace fintamath::detail {
 
-template <class T>
+template <typename T>
 struct Hash;
 
-template <class T>
+template <typename T>
 void hashCombine(size_t &seed, const T &v) noexcept {
   Hash<T> hasher;
   seed ^= hasher(v) + 0x9e3779b9 + (seed << 6) + (seed >> 2);
diff --git a/include/fintamath/expressions/IExpressionCRTP.hpp b/include/fintamath/expressions/IExpressionCRTP.hpp
index 68e86bd25..2ccde94db 100644
--- a/include/fintamath/expressions/IExpressionCRTP.hpp
+++ b/include/fintamath/expressions/IExpressionCRTP.hpp
@@ -24,7 +24,7 @@ class IExpressionCRTP_ : public IExpressionBaseCRTP<Derived> {
       return false;
     }
 
-    for (const auto i : stdv::iota(0U, lhsChildren.size())) {
+    for (size_t i = 0U; i < lhsChildren.size(); i++) {
       if (lhsChildren[i] != rhsChildren[i] && *lhsChildren[i] != *rhsChildren[i]) {
         return false;
       }
diff --git a/include/fintamath/functions/IFunctionCRTP.hpp b/include/fintamath/functions/IFunctionCRTP.hpp
index c523e6405..d65a87fb2 100644
--- a/include/fintamath/functions/IFunctionCRTP.hpp
+++ b/include/fintamath/functions/IFunctionCRTP.hpp
@@ -101,7 +101,7 @@ class IFunctionCRTP_ : public IFunction {
   bool doAnyArgsMatch(const ArgumentRefVector &argVect) const {
     using AnyArgsType = typename std::tuple_element_t<0, std::tuple<Args...>>;
 
-    return stdr::all_of(argVect, [](const auto &arg) {
+    return std::ranges::all_of(argVect, [](const auto &arg) {
       return is<AnyArgsType>(arg);
     });
   }
diff --git a/src/fintamath/core/Tokenizer.cpp b/src/fintamath/core/Tokenizer.cpp
index b5302dd89..0f208c099 100644
--- a/src/fintamath/core/Tokenizer.cpp
+++ b/src/fintamath/core/Tokenizer.cpp
@@ -38,7 +38,7 @@ TokenVector Tokenizer::tokenize(std::string str) {
 
 void Tokenizer::registerToken(const Token &token) {
   auto &tokens = getRegisteredTokens();
-  tokens.insert(stdr::upper_bound(tokens, token, [](const Token &lhs, const Token &rhs) {
+  tokens.insert(std::ranges::upper_bound(tokens, token, [](const Token &lhs, const Token &rhs) {
                   return lhs.size() > rhs.size();
                 }),
                 token);
diff --git a/src/fintamath/expressions/Expression.cpp b/src/fintamath/expressions/Expression.cpp
index 377f927c8..45cf78328 100644
--- a/src/fintamath/expressions/Expression.cpp
+++ b/src/fintamath/expressions/Expression.cpp
@@ -151,7 +151,7 @@ TermVector Expression::tokensToTerms(TokenVector &tokens) {
 
   TermVector terms(tokens.size());
 
-  for (const auto i : stdv::iota(0U, terms.size())) {
+  for (size_t i = 0U; i < terms.size(); i++) {
     terms[i] = parseTerm(tokens[i]);
   }
 
@@ -338,7 +338,7 @@ void Expression::fixOperatorTypes(TermVector &terms) {
     return;
   }
 
-  for (const auto i : stdv::iota(1U, terms.size() - 1)) {
+  for (size_t i = 1; i + 1 < terms.size(); i++) {
     auto &term = terms[i];
     const auto &termPrev = terms[i - 1];
 
@@ -351,7 +351,7 @@ void Expression::fixOperatorTypes(TermVector &terms) {
     }
   }
 
-  for (const auto i : stdv::iota(1U, terms.size() - 1) | stdv::reverse) {
+  for (size_t i = terms.size() - 1; i > 0; i--) {
     auto &term = terms[i];
     const auto &termNext = terms[i + 1];
 
@@ -457,7 +457,7 @@ void Expression::validateFunctionArgs(const IFunction &func, const ArgumentPtrVe
   const bool doesArgSizeMatch = !func.isVariadic() && args.size() == expectedArgTypes.size();
   MathObjectClass expectedType = expectedArgTypes.front();
 
-  for (const auto i : stdv::iota(0U, args.size())) {
+  for (size_t i = 0; i < args.size(); i++) {
     if (doesArgSizeMatch) {
       expectedType = expectedArgTypes[i];
     }
@@ -503,7 +503,7 @@ bool Expression::doesArgMatch(const MathObjectClass &expectedType, const Argumen
 namespace detail {
 
 std::unique_ptr<IMathObject> makeExpr(const IFunction &func, ArgumentPtrVector args) {
-  stdr::transform(args, args.begin(), &Expression::compress);
+  std::ranges::transform(args, args.begin(), &Expression::compress);
   Expression::validateFunctionArgs(func, args);
 
   if (const auto strToConstr = Expression::getExpressionMaker().find(func.getClass());
diff --git a/src/fintamath/expressions/ExpressionComparator.cpp b/src/fintamath/expressions/ExpressionComparator.cpp
index 60fb57dd6..8e57661e6 100644
--- a/src/fintamath/expressions/ExpressionComparator.cpp
+++ b/src/fintamath/expressions/ExpressionComparator.cpp
@@ -71,7 +71,7 @@ Ordering reverse(Ordering ordering);
 
 template <typename T>
 size_t getPositionOfFirstChildWithTerm(const ArgumentPtrVector &children) {
-  for (const auto i : stdv::iota(0U, children.size())) {
+  for (size_t i = 0; i < children.size(); i++) {
     if (containsIf(children[i], [](const ArgumentPtr &child) { return is<T>(child); })) {
       return i;
     }
@@ -429,7 +429,7 @@ ChildrenComparatorResult compareChildren(const ArgumentPtrVector &lhsChildren,
   auto size = std::min(std::max(lhsStart, rhsStart),
                        std::min(lhsChildren.size(), rhsChildren.size()));
 
-  for (const auto i : stdv::iota(0U, size)) {
+  for (size_t i = 0; i < size; i++) {
     const Ordering childrenComp = compare(lhsChildren[i], rhsChildren[i], options);
 
     if (childrenComp != Ordering::equal) {
diff --git a/src/fintamath/expressions/ExpressionUtils.cpp b/src/fintamath/expressions/ExpressionUtils.cpp
index 99ad079c3..7b3992eb2 100644
--- a/src/fintamath/expressions/ExpressionUtils.cpp
+++ b/src/fintamath/expressions/ExpressionUtils.cpp
@@ -90,7 +90,7 @@ bool containsIf(const ArgumentPtr &arg, const std::function<bool(const ArgumentP
 
   const ArgumentPtrVector &children = expr->getChildren();
 
-  return stdr::any_of(children, [&comp](const auto &child) {
+  return std::ranges::any_of(children, [&comp](const auto &child) {
     bool res = false;
 
     if (containsIf(child, comp)) {
@@ -226,12 +226,9 @@ std::pair<ArgumentPtr, ArgumentPtr> splitRational(const ArgumentPtr &arg) {
 ArgumentPtr negate(const ArgumentPtr &arg) {
   if (const auto expr = cast<IExpression>(arg)) {
     if (is<Add>(expr->getFunction())) {
-      auto negChildrenView =
-          expr->getChildren() |
-          stdv::transform([](const ArgumentPtr &child) {
-            return negate(child);
-          });
-      return makePolynom(Add{}, ArgumentPtrVector(negChildrenView.begin(), negChildrenView.end())); // TODO: use C++23 stdv::to
+      ArgumentPtrVector negChildren = expr->getChildren();
+      std::ranges::transform(negChildren, negChildren.begin(), &negate);
+      return makePolynom(Add{}, std::move(negChildren));
     }
 
     if (is<Mul>(expr->getFunction())) {
@@ -281,7 +278,7 @@ ArgumentPtrVector getPolynomChildren(const IFunction &func, const ArgumentPtr &a
 std::vector<std::string> argumentVectorToStringVector(const ArgumentPtrVector &args) {
   std::vector<std::string> argStrings(args.size());
 
-  for (const auto i : stdv::iota(0U, argStrings.size())) {
+  for (size_t i = 0; i < argStrings.size(); i++) {
     argStrings[i] = args[i].get()->toString();
   }
 
diff --git a/src/fintamath/expressions/IExpression.cpp b/src/fintamath/expressions/IExpression.cpp
index 5a358a5d4..6be1d77ea 100644
--- a/src/fintamath/expressions/IExpression.cpp
+++ b/src/fintamath/expressions/IExpression.cpp
@@ -41,8 +41,8 @@ std::vector<Variable> IExpression::getVariables() const {
     }
   }
 
-  stdr::sort(vars, std::less{}, &Variable::toString);
-  auto unique = stdr::unique(vars);
+  std::ranges::sort(vars, std::less{}, &Variable::toString);
+  auto unique = std::ranges::unique(vars);
   vars.erase(unique.begin(), unique.end());
 
   return vars;
diff --git a/src/fintamath/expressions/binary/CompExpr.cpp b/src/fintamath/expressions/binary/CompExpr.cpp
index e7f16fc07..89c539209 100644
--- a/src/fintamath/expressions/binary/CompExpr.cpp
+++ b/src/fintamath/expressions/binary/CompExpr.cpp
@@ -216,7 +216,7 @@ ArgumentPtr CompExpr::rateSimplify(const IFunction &func, const ArgumentPtr &lhs
     return {};
   }
 
-  for (auto &child : stdv::drop(children, 1)) {
+  for (auto &child : children | std::views::drop(1)) {
     child = divExpr(child, rate);
   }
 
diff --git a/src/fintamath/expressions/binary/DerivativeExpr.cpp b/src/fintamath/expressions/binary/DerivativeExpr.cpp
index 340e86e08..2921c1580 100644
--- a/src/fintamath/expressions/binary/DerivativeExpr.cpp
+++ b/src/fintamath/expressions/binary/DerivativeExpr.cpp
@@ -139,7 +139,7 @@ ArgumentPtr DerivativeExpr::exprSimplify(const std::shared_ptr<const IExpression
 ArgumentPtr DerivativeExpr::addSimplify(const ArgumentPtrVector &children, const std::shared_ptr<const Variable> &var) {
   ArgumentPtrVector newChildren = children;
 
-  stdr::transform(newChildren, newChildren.begin(), [&var](const ArgumentPtr &child) {
+  std::ranges::transform(newChildren, newChildren.begin(), [&var](const ArgumentPtr &child) {
     return derivativeExpr(child, var);
   });
 
diff --git a/src/fintamath/expressions/binary/DivExpr.cpp b/src/fintamath/expressions/binary/DivExpr.cpp
index 0c92896ff..a269809a6 100644
--- a/src/fintamath/expressions/binary/DivExpr.cpp
+++ b/src/fintamath/expressions/binary/DivExpr.cpp
@@ -188,11 +188,9 @@ ArgumentPtr DivExpr::mulSimplify(const SimplifyFunctionVector &simplFuncs,
   const size_t rhsChildrenSizeInitial = rhsChildren.size();
 
   // TODO: use more efficient algorithm
-  for (const auto i : stdv::iota(0U, lhsChildren.size())) {
-    auto &lhsChild = lhsChildren[i];
-
-    for (const auto j : stdv::iota(0U, rhsChildren.size())) {
-      const auto &rhsChild = rhsChildren[j];
+  for (auto &lhsChild : lhsChildren) {
+    for (size_t i = 0; i < rhsChildren.size(); i++) {
+      const auto &rhsChild = rhsChildren[i];
 
       ArgumentPtr res = useSimplifyFunctions(simplFuncs,
                                              func,
@@ -201,7 +199,7 @@ ArgumentPtr DivExpr::mulSimplify(const SimplifyFunctionVector &simplFuncs,
 
       if (res && !is<Rational>(res) && *res != *makeExpr(func, lhsChild, rhsChild)) {
         lhsChild = std::move(res);
-        rhsChildren.erase(rhsChildren.begin() + j);
+        rhsChildren.erase(rhsChildren.begin() + static_cast<ptrdiff_t>(i));
         break;
       }
     }
@@ -394,7 +392,7 @@ std::pair<ArgumentPtr, ArgumentPtr> DivExpr::mulSumSimplify(const ArgumentPtr &l
 
   ArgumentPtrVector multiplicators;
 
-  for (const auto &rhsChild : rhsChildren | stdv::drop(1)) {
+  for (const auto &rhsChild : rhsChildren | std::views::drop(1)) {
     multiplicators.emplace_back(mulExpr(rhsChild, result));
   }
 
diff --git a/src/fintamath/expressions/binary/PowExpr.cpp b/src/fintamath/expressions/binary/PowExpr.cpp
index 647f8bbe7..de3616aba 100644
--- a/src/fintamath/expressions/binary/PowExpr.cpp
+++ b/src/fintamath/expressions/binary/PowExpr.cpp
@@ -137,10 +137,10 @@ PowExpr::SimplifyFunctionVector PowExpr::getFunctionsForPostSimplify() const {
 Integer PowExpr::generateFirstNum(const Integer &countOfOne) {
   Integer n = 0;
 
-  for ([[maybe_unused]] const auto _ : stdv::iota(0U, countOfOne)) {
+  repeat(countOfOne, [&]() {
     n <<= 1;
     n |= 1;
-  }
+  });
 
   return n;
 }
@@ -193,21 +193,21 @@ ArgumentPtr PowExpr::sumPolynomSimplify(const ArgumentPtr &expr, const Integer &
 
   ArgumentPtrVector newChildren;
 
-  for ([[maybe_unused]] const auto _ : stdv::iota(0U, combins)) {
+  repeat(combins, [&]() {
     std::vector<Integer> vectOfPows = getPartition(bitNumber, Integer(variableCount));
     bitNumber = generateNextNumber(bitNumber);
 
     ArgumentPtrVector mulExprChildren;
     mulExprChildren.emplace_back(multinomialCoefficient(power, vectOfPows).clone());
 
-    for (const auto i : stdv::iota(0U, variableCount)) {
+    for (size_t i = 0; i < variableCount; i++) {
       ArgumentPtr powExprChild = powExpr(polynom[i], vectOfPows[i].clone());
       mulExprChildren.emplace_back(std::move(powExprChild));
     }
 
     ArgumentPtr mulExprChild = mulExpr(std::move(mulExprChildren));
     newChildren.emplace_back(std::move(mulExprChild));
-  }
+  });
 
   return addExpr(std::move(newChildren));
 }
diff --git a/src/fintamath/expressions/interfaces/IPolynomExpression.cpp b/src/fintamath/expressions/interfaces/IPolynomExpression.cpp
index 74509803d..bba48aab8 100644
--- a/src/fintamath/expressions/interfaces/IPolynomExpression.cpp
+++ b/src/fintamath/expressions/interfaces/IPolynomExpression.cpp
@@ -48,7 +48,7 @@ std::string IPolynomExpression::toString() const {
 
   result += childToString(*oper, children.front(), {});
 
-  for (const auto i : stdv::iota(1U, children.size())) {
+  for (size_t i = 1; i < children.size(); i++) {
     const std::string childStr = childToString(*oper, children[i], children[i - 1]);
 
     if (childStr.size() > 2 && childStr[0] == ' ' && std::isdigit(childStr[1]) && std::isdigit(result.back())) {
@@ -225,7 +225,7 @@ void IPolynomExpression::setChildren(const ArgumentPtrVector &childVect) {
 }
 
 void IPolynomExpression::sort() {
-  stdr::stable_sort(children, [this](const ArgumentPtr &lhs, const ArgumentPtr &rhs) {
+  std::ranges::stable_sort(children, [this](const ArgumentPtr &lhs, const ArgumentPtr &rhs) {
     return compare(lhs, rhs) == std::strong_ordering::greater;
   });
 }
diff --git a/src/fintamath/expressions/polynomial/AddExpr.cpp b/src/fintamath/expressions/polynomial/AddExpr.cpp
index af2354d9c..62ab8e2a8 100644
--- a/src/fintamath/expressions/polynomial/AddExpr.cpp
+++ b/src/fintamath/expressions/polynomial/AddExpr.cpp
@@ -236,7 +236,7 @@ ArgumentPtr AddExpr::mulLogSimplify(const IFunction & /*func*/, const ArgumentPt
 std::vector<size_t> AddExpr::findLogarithms(const ArgumentPtrVector &children) {
   std::vector<size_t> indices;
 
-  for (const auto i : stdv::iota(0U, children.size())) {
+  for (size_t i = 0; i < children.size(); i++) {
     if (const auto childExpr = cast<const IExpression>(children[i]);
         childExpr && is<Log>(childExpr->getFunction())) {
 
diff --git a/src/fintamath/expressions/polynomial/OrExpr.cpp b/src/fintamath/expressions/polynomial/OrExpr.cpp
index 3fd2bbe34..5fd63d6e1 100644
--- a/src/fintamath/expressions/polynomial/OrExpr.cpp
+++ b/src/fintamath/expressions/polynomial/OrExpr.cpp
@@ -145,7 +145,7 @@ ArgumentPtr OrExpr::andSimplify(const IFunction & /*func*/, const ArgumentPtr &l
 
   size_t resolutionIndex = lhsChildren.size();
 
-  for (const auto i : stdv::iota(0U, lhsChildren.size())) {
+  for (size_t i = 0; i < lhsChildren.size(); i++) {
     ArgumentPtr lhsSubChild = lhsChildren[i];
     ArgumentPtr rhsSubChild = rhsChildren[i];
 
diff --git a/src/fintamath/functions/IFunction.cpp b/src/fintamath/functions/IFunction.cpp
index a85518b1b..eee5bd9ed 100644
--- a/src/fintamath/functions/IFunction.cpp
+++ b/src/fintamath/functions/IFunction.cpp
@@ -17,7 +17,7 @@ void IFunction::validateArgsSize(const ArgumentRefVector &argVect) const {
 
   std::vector<std::string> argNameVect(argVect.size());
 
-  for (const auto i : stdv::iota(0U, argNameVect.size())) {
+  for (size_t i = 0; i < argNameVect.size(); i++) {
     argNameVect[i] = argVect[i].get().toString();
   }
 
diff --git a/src/fintamath/functions/calculus/Max.cpp b/src/fintamath/functions/calculus/Max.cpp
index 34c83fe7c..8c2e58574 100644
--- a/src/fintamath/functions/calculus/Max.cpp
+++ b/src/fintamath/functions/calculus/Max.cpp
@@ -15,7 +15,7 @@ namespace fintamath {
 std::unique_ptr<IMathObject> Max::call(const ArgumentRefVector &argVect) const {
   std::reference_wrapper res = cast<IComparable>(argVect.front().get());
 
-  for (const auto &arg : argVect | stdv::drop(1)) {
+  for (const auto &arg : argVect | std::views::drop(1)) {
     if (is<Complex>(arg)) {
       return {};
     }
diff --git a/src/fintamath/functions/calculus/Min.cpp b/src/fintamath/functions/calculus/Min.cpp
index 6010020b4..a3bd2338a 100644
--- a/src/fintamath/functions/calculus/Min.cpp
+++ b/src/fintamath/functions/calculus/Min.cpp
@@ -15,7 +15,7 @@ namespace fintamath {
 std::unique_ptr<IMathObject> Min::call(const ArgumentRefVector &argVect) const {
   std::reference_wrapper res = cast<IComparable>(argVect.front().get());
 
-  for (const auto &arg : argVect | stdv::drop(1)) {
+  for (const auto &arg : argVect | std::views::drop(1)) {
     if (is<Complex>(arg)) {
       return {};
     }
diff --git a/src/fintamath/numbers/Rational.cpp b/src/fintamath/numbers/Rational.cpp
index f25159cfc..7d513a96a 100644
--- a/src/fintamath/numbers/Rational.cpp
+++ b/src/fintamath/numbers/Rational.cpp
@@ -27,7 +27,7 @@ Rational::Rational(const std::string &str) {
   }
 
   int64_t firstDigitNum = 0;
-  const int64_t firstDotNum = stdr::distance(str.begin(), stdr::find(str, '.'));
+  const int64_t firstDotNum = std::ranges::distance(str.begin(), std::ranges::find(str, '.'));
 
   bool isNegative = false;
   if (str.front() == '-') {
diff --git a/tests/src/core/CoreUtilsTests.cpp b/tests/src/core/CoreUtilsTests.cpp
index 32abc5e91..0f709b553 100644
--- a/tests/src/core/CoreUtilsTests.cpp
+++ b/tests/src/core/CoreUtilsTests.cpp
@@ -2,4 +2,6 @@
 
 #include "fintamath/core/CoreUtils.hpp"
 
-// Nothing to test yet
+TEST(CoreUtilsTests, repeatTest) {
+  // TODO: implement
+}
diff --git a/tests/src/core/HashTests.cpp b/tests/src/core/HashTests.cpp
index 23b67de50..5e17f9b8e 100644
--- a/tests/src/core/HashTests.cpp
+++ b/tests/src/core/HashTests.cpp
@@ -60,38 +60,38 @@ TEST(HashTests, hashCombineTest) {
 
 TEST(HashTests, hashTupleTest) {
   {
-    std::tuple tuple1 = {123, 1.23, "abc"};
-    std::tuple tuple2 = {123, 1.23, "abc"};
+    std::tuple tuple1 = {123, 1.23, std::string("abc")};
+    std::tuple tuple2 = {123, 1.23, std::string("abc")};
 
     EXPECT_EQ(Hash<decltype(tuple1)>{}(tuple1), Hash<decltype(tuple2)>{}(tuple2));
   }
   {
-    std::tuple tuple1 = {124, 1.23, "abc"};
-    std::tuple tuple2 = {123, 1.23, "abc"};
+    std::tuple tuple1 = {124, 1.23, std::string("abc")};
+    std::tuple tuple2 = {123, 1.23, std::string("abc")};
 
     EXPECT_NE(Hash<decltype(tuple1)>{}(tuple1), Hash<decltype(tuple2)>{}(tuple2));
   }
   {
-    std::tuple tuple1 = {123, 1.23, "abc"};
-    std::tuple tuple2 = {123, 2.23, "abc"};
+    std::tuple tuple1 = {123, 1.23, std::string("abc")};
+    std::tuple tuple2 = {123, 2.23, std::string("abc")};
 
     EXPECT_NE(Hash<decltype(tuple1)>{}(tuple1), Hash<decltype(tuple2)>{}(tuple2));
   }
   {
     std::tuple tuple1 = {123, 1.23, "abd"};
-    std::tuple tuple2 = {123, 1.23, "abc"};
+    std::tuple tuple2 = {123, 1.23, std::string("abc")};
 
     EXPECT_NE(Hash<decltype(tuple1)>{}(tuple1), Hash<decltype(tuple2)>{}(tuple2));
   }
   {
     std::tuple tuple1 = {123, "abd", 1.23};
-    std::tuple tuple2 = {123, 1.23, "abc"};
+    std::tuple tuple2 = {123, 1.23, std::string("abc")};
 
     EXPECT_NE(Hash<decltype(tuple1)>{}(tuple1), Hash<decltype(tuple2)>{}(tuple2));
   }
   {
     std::tuple tuple1 = {123, 1.23, "abd"};
-    std::tuple tuple2 = {1.23, "abc", 123};
+    std::tuple tuple2 = {1.23, std::string("abc"), 123};
 
     EXPECT_NE(Hash<decltype(tuple1)>{}(tuple1), Hash<decltype(tuple2)>{}(tuple2));
   }