diff --git a/lib/mathlib.cpp b/lib/mathlib.cpp
index b4670cc1e..960096072 100644
--- a/lib/mathlib.cpp
+++ b/lib/mathlib.cpp
@@ -803,6 +803,9 @@ static std::string intsuffix(const std::string & first, const std::string & seco
 
 std::string MathLib::add(const std::string & first, const std::string & second)
 {
+#ifdef TEST_MATHLIB_VALUE
+    return (value(first) + value(second)).str();
+#else
     if (MathLib::isInt(first) && MathLib::isInt(second)) {
         return toString(toLongNumber(first) + toLongNumber(second)) + intsuffix(first, second);
     }
@@ -817,10 +820,14 @@ std::string MathLib::add(const std::string & first, const std::string & second)
         d1 *= 10.0;
 
     return toString(d1 + d2);
+#endif
 }
 
 std::string MathLib::subtract(const std::string &first, const std::string &second)
 {
+#ifdef TEST_MATHLIB_VALUE
+    return (value(first) - value(second)).str();
+#else
     if (MathLib::isInt(first) && MathLib::isInt(second)) {
         return toString(toLongNumber(first) - toLongNumber(second)) + intsuffix(first, second);
     }
@@ -838,20 +845,31 @@ std::string MathLib::subtract(const std::string &first, const std::string &secon
         d1 *= 10.0;
 
     return toString(d1 - d2);
+#endif
 }
 
 std::string MathLib::incdec(const std::string & var, const std::string & op)
 {
+#ifdef TEST_MATHLIB_VALUE
+    if (op == "++")
+        return value(var).add(1).str();
+    else if (op == "--")
+        return value(var).add(-1).str();
+#else
     if (op == "++")
         return MathLib::add(var, "1");
     else if (op == "--")
         return MathLib::subtract(var, "1");
+#endif
 
     throw InternalError(0, std::string("Unexpected operation '") + op + "' in MathLib::incdec(). Please report this to Cppcheck developers.");
 }
 
 std::string MathLib::divide(const std::string &first, const std::string &second)
 {
+#ifdef TEST_MATHLIB_VALUE
+    return (value(first) / value(second)).str();
+#else
     if (MathLib::isInt(first) && MathLib::isInt(second)) {
         const bigint a = toLongNumber(first);
         const bigint b = toLongNumber(second);
@@ -863,23 +881,29 @@ std::string MathLib::divide(const std::string &first, const std::string &second)
     } else if (isNullValue(second)) {
         if (isNullValue(first))
             return "nan.0";
-        const int sign_first = (isPositive(first)) ? 1 : -1;
-        const int sign_second = (isPositive(second)) ? 1 : -1;
-        return (sign_first*sign_second == 1) ? "inf.0" : "-inf.0";
+        return isPositive(first) ? "inf.0" : "-inf.0";
     }
     return toString(toDoubleNumber(first) / toDoubleNumber(second));
+#endif
 }
 
 std::string MathLib::multiply(const std::string &first, const std::string &second)
 {
+#ifdef TEST_MATHLIB_VALUE
+    return (value(first) * value(second)).str();
+#else
     if (MathLib::isInt(first) && MathLib::isInt(second)) {
         return toString(toLongNumber(first) * toLongNumber(second)) + intsuffix(first, second);
     }
     return toString(toDoubleNumber(first) * toDoubleNumber(second));
+#endif
 }
 
 std::string MathLib::mod(const std::string &first, const std::string &second)
 {
+#ifdef TEST_MATHLIB_VALUE
+    return (value(first) % value(second)).str();
+#else
     if (MathLib::isInt(first) && MathLib::isInt(second)) {
         const bigint b = toLongNumber(second);
         if (b == 0)
@@ -887,6 +911,7 @@ std::string MathLib::mod(const std::string &first, const std::string &second)
         return toString(toLongNumber(first) % b) + intsuffix(first, second);
     }
     return toString(std::fmod(toDoubleNumber(first),toDoubleNumber(second)));
+#endif
 }
 
 std::string MathLib::calculate(const std::string &first, const std::string &second, char action)
diff --git a/test/testmathlib.cpp b/test/testmathlib.cpp
index 7625a0de4..9a4a01aeb 100644
--- a/test/testmathlib.cpp
+++ b/test/testmathlib.cpp
@@ -148,14 +148,19 @@ private:
 
     void calculate1() const {
         ASSERT_EQUALS("0"    , MathLib::calculate("2"    , "1"    , '%'));
-        ASSERT_EQUALS("0.0"  , MathLib::calculate("2.0"  , "1.0"  , '%'));
         ASSERT_EQUALS("2"    , MathLib::calculate("12"   , "5"   , '%'));
         ASSERT_EQUALS("1"    , MathLib::calculate("100"  , "3"   , '%'));
+
+#ifndef TEST_MATHLIB_VALUE
+        // floating point modulo is not defined in C/C++
+        ASSERT_EQUALS("0.0"  , MathLib::calculate("2.0"  , "1.0"  , '%'));
         ASSERT_EQUALS("12.0" , MathLib::calculate("12.0" , "13.0" , '%'));
         ASSERT_EQUALS("1.3"  , MathLib::calculate("5.3"  , "2.0" , '%'));
         ASSERT_EQUALS("1.7"  , MathLib::calculate("18.5" , "4.2" , '%'));
-        ASSERT_THROW(MathLib::calculate("123", "0", '%'), InternalError); // throw
         MathLib::calculate("123", "0.0", '%'); // don't throw
+#endif
+
+        ASSERT_THROW(MathLib::calculate("123", "0", '%'), InternalError); // throw
 
         ASSERT_EQUALS("0"    , MathLib::calculate("1"    , "1"    , '^'));
         ASSERT_EQUALS("3"    , MathLib::calculate("2"    , "1"    , '^'));
@@ -815,7 +820,7 @@ private:
         ASSERT_EQUALS("inf.0", MathLib::divide("3.0", "0.f")); // inf (#5875)
         ASSERT_EQUALS("-inf.0", MathLib::divide("-3.0", "0.0")); // -inf (#5142)
         ASSERT_EQUALS("-inf.0", MathLib::divide("-3.0", "0.0f")); // -inf (#5142)
-        ASSERT_EQUALS("inf.0", MathLib::divide("-3.0", "-0.0f")); // inf (#5142)
+        ASSERT_EQUALS("-inf.0", MathLib::divide("-3.0", "-0.0f")); // inf (#5142)
     }
 
     void isdec(void) const {