diff --git a/api/src/main/java/com/instancify/scriptify/api/script/function/ScriptFunctionManager.java b/api/src/main/java/com/instancify/scriptify/api/script/function/ScriptFunctionManager.java
index e615048..948a8fe 100644
--- a/api/src/main/java/com/instancify/scriptify/api/script/function/ScriptFunctionManager.java
+++ b/api/src/main/java/com/instancify/scriptify/api/script/function/ScriptFunctionManager.java
@@ -1,6 +1,7 @@
 package com.instancify.scriptify.api.script.function;
 
 import com.instancify.scriptify.api.script.function.definition.ScriptFunctionDefinition;
+import com.instancify.scriptify.api.script.function.definition.factory.ScriptFunctionDefinitionFactory;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.annotations.UnmodifiableView;
 
@@ -11,6 +12,20 @@
  */
 public interface ScriptFunctionManager {
 
+    /**
+     * Retrieves function definition factory.
+     *
+     * @return ScriptFunctionDefinitionFactory
+     */
+    ScriptFunctionDefinitionFactory getFunctionDefinitionFactory();
+
+    /**
+     * Set the function definition factory.
+     *
+     * @param factory ScriptFunctionDefinitionFactory
+     */
+    void setFunctionDefinitionFactory(ScriptFunctionDefinitionFactory factory);
+
     /**
      * Retrieves all registered functions.
      *
diff --git a/api/src/main/java/com/instancify/scriptify/api/script/function/definition/factory/ScriptFunctionDefinitionFactory.java b/api/src/main/java/com/instancify/scriptify/api/script/function/definition/factory/ScriptFunctionDefinitionFactory.java
new file mode 100644
index 0000000..336a357
--- /dev/null
+++ b/api/src/main/java/com/instancify/scriptify/api/script/function/definition/factory/ScriptFunctionDefinitionFactory.java
@@ -0,0 +1,19 @@
+package com.instancify.scriptify.api.script.function.definition.factory;
+
+import com.instancify.scriptify.api.script.function.ScriptFunction;
+import com.instancify.scriptify.api.script.function.definition.ScriptFunctionDefinition;
+
+/**
+ * Script function definition factory.
+ * Allows to create custom factory for creating specific definitions.
+ */
+public interface ScriptFunctionDefinitionFactory {
+
+    /**
+     * Creates a function definition.
+     *
+     * @param function ScriptFunction
+     * @return ScriptFunctionDefinition
+     */
+    ScriptFunctionDefinition create(ScriptFunction function);
+}
diff --git a/build.gradle.kts b/build.gradle.kts
index f1156d3..2fd6d2e 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -12,7 +12,7 @@ java {
 
 allprojects {
     group = "com.instancify.scriptify"
-    version = "1.4.2-SNAPSHOT"
+    version = "1.4.3-SNAPSHOT"
 }
 
 subprojects {
diff --git a/common/src/main/java/com/instancify/scriptify/common/script/function/CommonFunctionManager.java b/common/src/main/java/com/instancify/scriptify/common/script/function/CommonFunctionManager.java
index bc87d18..debcc5e 100644
--- a/common/src/main/java/com/instancify/scriptify/common/script/function/CommonFunctionManager.java
+++ b/common/src/main/java/com/instancify/scriptify/common/script/function/CommonFunctionManager.java
@@ -1,5 +1,6 @@
 package com.instancify.scriptify.common.script.function;
 
+import com.instancify.scriptify.api.script.function.definition.factory.ScriptFunctionDefinitionFactory;
 import com.instancify.scriptify.common.script.function.impl.crypto.ScriptFunctionBase64Decode;
 import com.instancify.scriptify.common.script.function.impl.crypto.ScriptFunctionBase64Encode;
 import com.instancify.scriptify.common.script.function.impl.crypto.ScriptFunctionMD5;
@@ -18,6 +19,15 @@
 public class CommonFunctionManager extends StandardFunctionManager {
 
     public CommonFunctionManager() {
+        this.init();
+    }
+
+    public CommonFunctionManager(ScriptFunctionDefinitionFactory functionDefinitionFactory) {
+        super(functionDefinitionFactory);
+        this.init();
+    }
+
+    private void init() {
         this.register(new ScriptFunctionPrint());
         this.register(new ScriptFunctionExistsFile());
         this.register(new ScriptFunctionDeleteFile());
diff --git a/core/src/main/java/com/instancify/scriptify/core/script/constant/StandardConstantManager.java b/core/src/main/java/com/instancify/scriptify/core/script/constant/StandardConstantManager.java
index b460636..d65f4bf 100644
--- a/core/src/main/java/com/instancify/scriptify/core/script/constant/StandardConstantManager.java
+++ b/core/src/main/java/com/instancify/scriptify/core/script/constant/StandardConstantManager.java
@@ -7,6 +7,7 @@
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Objects;
 
 public class StandardConstantManager implements ScriptConstantManager {
 
@@ -19,6 +20,7 @@ public class StandardConstantManager implements ScriptConstantManager {
 
     @Override
     public void register(ScriptConstant constant) {
+        Objects.requireNonNull(constant, "constant cannot be null");
         if (!constants.containsKey(constant.getName())) {
             constants.put(constant.getName(), constant);
         } else {
diff --git a/core/src/main/java/com/instancify/scriptify/core/script/function/StandardFunctionManager.java b/core/src/main/java/com/instancify/scriptify/core/script/function/StandardFunctionManager.java
index 81e618a..50d220a 100644
--- a/core/src/main/java/com/instancify/scriptify/core/script/function/StandardFunctionManager.java
+++ b/core/src/main/java/com/instancify/scriptify/core/script/function/StandardFunctionManager.java
@@ -3,16 +3,37 @@
 import com.instancify.scriptify.api.script.function.ScriptFunction;
 import com.instancify.scriptify.api.script.function.ScriptFunctionManager;
 import com.instancify.scriptify.api.script.function.definition.ScriptFunctionDefinition;
-import com.instancify.scriptify.core.script.function.definition.ScriptFunctionDefinitionImpl;
+import com.instancify.scriptify.api.script.function.definition.factory.ScriptFunctionDefinitionFactory;
+import com.instancify.scriptify.core.script.function.definition.factory.StandardFunctionDefinitionFactory;
 import org.jetbrains.annotations.UnmodifiableView;
 
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Objects;
 
 public class StandardFunctionManager implements ScriptFunctionManager {
 
     private final Map<String, ScriptFunctionDefinition> functions = new HashMap<>();
+    private ScriptFunctionDefinitionFactory functionDefinitionFactory;
+
+    public StandardFunctionManager() {
+        this(new StandardFunctionDefinitionFactory());
+    }
+
+    public StandardFunctionManager(ScriptFunctionDefinitionFactory functionDefinitionFactory) {
+        this.setFunctionDefinitionFactory(functionDefinitionFactory);
+    }
+
+    @Override
+    public ScriptFunctionDefinitionFactory getFunctionDefinitionFactory() {
+        return functionDefinitionFactory;
+    }
+
+    @Override
+    public void setFunctionDefinitionFactory(ScriptFunctionDefinitionFactory functionDefinitionFactory) {
+        this.functionDefinitionFactory = Objects.requireNonNull(functionDefinitionFactory, "functionDefinitionFactory cannot be null");
+    }
 
     @Override
     public @UnmodifiableView Map<String, ScriptFunctionDefinition> getFunctions() {
@@ -21,8 +42,13 @@ public class StandardFunctionManager implements ScriptFunctionManager {
 
     @Override
     public void register(ScriptFunction function) {
+        Objects.requireNonNull(function, "function cannot be null");
         if (!functions.containsKey(function.getName())) {
-            functions.put(function.getName(), new ScriptFunctionDefinitionImpl(function));
+            ScriptFunctionDefinition definition = functionDefinitionFactory.create(function);
+            if (definition == null) {
+                throw new UnsupportedOperationException("Function definition factory has not created definition");
+            }
+            functions.put(function.getName(), definition);
         } else {
             throw new IllegalStateException("The function with name '" + function.getName() + "' already exists");
         }
diff --git a/core/src/main/java/com/instancify/scriptify/core/script/function/definition/factory/StandardFunctionDefinitionFactory.java b/core/src/main/java/com/instancify/scriptify/core/script/function/definition/factory/StandardFunctionDefinitionFactory.java
new file mode 100644
index 0000000..e707323
--- /dev/null
+++ b/core/src/main/java/com/instancify/scriptify/core/script/function/definition/factory/StandardFunctionDefinitionFactory.java
@@ -0,0 +1,14 @@
+package com.instancify.scriptify.core.script.function.definition.factory;
+
+import com.instancify.scriptify.api.script.function.ScriptFunction;
+import com.instancify.scriptify.api.script.function.definition.ScriptFunctionDefinition;
+import com.instancify.scriptify.api.script.function.definition.factory.ScriptFunctionDefinitionFactory;
+import com.instancify.scriptify.core.script.function.definition.ScriptFunctionDefinitionImpl;
+
+public class StandardFunctionDefinitionFactory implements ScriptFunctionDefinitionFactory {
+
+    @Override
+    public ScriptFunctionDefinition create(ScriptFunction function) {
+        return new ScriptFunctionDefinitionImpl(function);
+    }
+}