diff --git a/src/Library/EffectParameter.hpp b/src/Library/EffectParameter.hpp
index 01096a1..4040a26 100644
--- a/src/Library/EffectParameter.hpp
+++ b/src/Library/EffectParameter.hpp
@@ -1,7 +1,8 @@
 #ifndef CREATURELIB_EFFECTPARAMETER_HPP
 #define CREATURELIB_EFFECTPARAMETER_HPP
+#include <Arbutils/ConstString.hpp>
 #include <Arbutils/Enum.hpp>
-#include <cstring>
+#include <variant>
 #include "Exceptions/CreatureException.hpp"
 
 namespace CreatureLib::Library {
@@ -10,24 +11,18 @@ namespace CreatureLib::Library {
     class EffectParameter {
     private:
         EffectParameterType _type = EffectParameterType::None;
-        union {
-            bool _b;
-            int64_t _i;
-            const std::string _s;
-            float _f;
-        };
+        std::variant<bool, int64_t, float, Arbutils::CaseInsensitiveConstString> _value;
 
     public:
         EffectParameter() : _type(EffectParameterType::None){};
-        explicit EffectParameter(bool b) : _type(EffectParameterType::Bool), _b(b){};
-        explicit EffectParameter(int64_t i) : _type(EffectParameterType::Int), _i(i){};
-        explicit EffectParameter(float f) : _type(EffectParameterType::Float), _f(f){};
-        explicit EffectParameter(const std::string& s) : _type(EffectParameterType::String), _s(s){};
+        explicit EffectParameter(bool b) : _type(EffectParameterType::Bool), _value(b){};
+        explicit EffectParameter(int64_t i) : _type(EffectParameterType::Int), _value(i){};
+        explicit EffectParameter(float f) : _type(EffectParameterType::Float), _value(f){};
+        explicit EffectParameter(const Arbutils::CaseInsensitiveConstString& s)
+            : _type(EffectParameterType::String), _value(s){};
         EffectParameter(const EffectParameter& other) = delete;
         EffectParameter& operator=(const EffectParameter& other) = delete;
 
-        ~EffectParameter() {}
-
         EffectParameterType GetType() const noexcept { return _type; }
         bool AsBool() const {
             if (_type != EffectParameterType::Bool) {
@@ -35,7 +30,7 @@ namespace CreatureLib::Library {
                 ss << "Cast effect parameter to bool, but was " << EffectParameterTypeHelper::ToString(_type);
                 throw CreatureException(ss.str());
             }
-            return _b;
+            return std::get<bool>(_value);
         }
         int64_t AsInt() const {
             if (_type != EffectParameterType::Int) {
@@ -43,7 +38,7 @@ namespace CreatureLib::Library {
                 ss << "Cast effect parameter to int, but was " << EffectParameterTypeHelper::ToString(_type);
                 throw CreatureException(ss.str());
             }
-            return _i;
+            return std::get<int64_t>(_value);
         }
         float AsFloat() const {
             if (_type != EffectParameterType::Float) {
@@ -51,15 +46,15 @@ namespace CreatureLib::Library {
                 ss << "Cast effect parameter to float, but was " << EffectParameterTypeHelper::ToString(_type);
                 throw CreatureException(ss.str());
             }
-            return _f;
+            return std::get<float>(_value);
         }
-        const std::string& AsString() const {
+        const Arbutils::CaseInsensitiveConstString& AsString() const {
             if (_type != EffectParameterType::String) {
                 std::stringstream ss;
                 ss << "Cast effect parameter to string, but was " << EffectParameterTypeHelper::ToString(_type);
                 throw CreatureException(ss.str());
             }
-            return _s;
+            return std::get<Arbutils::CaseInsensitiveConstString>(_value);
         }
     };
 }
diff --git a/tests/LibraryTests/EffectParameterTests.cpp b/tests/LibraryTests/EffectParameterTests.cpp
index a64a747..6fb6669 100644
--- a/tests/LibraryTests/EffectParameterTests.cpp
+++ b/tests/LibraryTests/EffectParameterTests.cpp
@@ -16,7 +16,7 @@ TEST_CASE("Int EffectParameter", "[Library]") {
 }
 
 TEST_CASE("String EffectParameter", "[Library]") {
-    auto p = EffectParameter(std::string("foobar"));
+    auto p = EffectParameter((Arbutils::CaseInsensitiveConstString) "foobar"_cnc);
     REQUIRE(p.AsString() == "foobar");
 }