diff --git a/CHANGELOG.md b/CHANGELOG.md
index b46a050..ef9c232 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,12 @@
 # (MODX)EvolutionCMS.libraries.ddTools changelog
 
 
+## Version 0.45.1 (2021-03-12)
+* \* `\DDTools\ObjectTools::extend`:
+	* \* Recursion is called only if source value is an object or array.
+	* \* Optimization.
+
+
 ## Version 0.45 (2021-03-11)
 * \+ `\DDTools\Response::isSuccess`: The new public method.
 
diff --git a/CHANGELOG_ru.md b/CHANGELOG_ru.md
index 5d6b094..c6ec1f2 100644
--- a/CHANGELOG_ru.md
+++ b/CHANGELOG_ru.md
@@ -1,6 +1,12 @@
 # (MODX)EvolutionCMS.libraries.ddTools changelog
 
 
+## Версия 0.45.1 (2021-03-12)
+* \* `\DDTools\ObjectTools::extend`:
+	* \* Рекурсия вызывается только в том случае, если исходным значением является объект или массив.
+	* \* Оптимизация.
+
+
 ## Версия 0.45 (2021-03-11)
 * \+ `\DDTools\Response::isSuccess`: Новый публичный метод.
 
diff --git a/composer.json b/composer.json
index 53b54b0..e43bca7 100644
--- a/composer.json
+++ b/composer.json
@@ -1,7 +1,7 @@
 {
 	"name": "dd/evolutioncms-libraries-ddtools",
 	"type": "modxevo-library-ddtools",
-	"version": "0.45.0",
+	"version": "0.45.1",
 	"description": "A library with various tools facilitating your work.",
 	"keywords": [
 		"modx",
diff --git a/modx.ddtools.class.php b/modx.ddtools.class.php
index d712d68..530322b 100644
--- a/modx.ddtools.class.php
+++ b/modx.ddtools.class.php
@@ -1,7 +1,7 @@
 <?php
 /**
  * EvolutionCMS.libraries.ddTools
- * @version 0.45 (2021-03-11)
+ * @version 0.45.1 (2021-03-12)
  * 
  * @see README.md
  * 
diff --git a/src/ObjectTools/ObjectTools.php b/src/ObjectTools/ObjectTools.php
index 044f1ec..a687638 100644
--- a/src/ObjectTools/ObjectTools.php
+++ b/src/ObjectTools/ObjectTools.php
@@ -164,7 +164,7 @@ public static function convertType($params){
 	
 	/**
 	 * extend
-	 * @version 1.3 (2020-04-30)
+	 * @version 1.3.7 (2021-03-12)
 	 * 
 	 * @see README.md
 	 * 
@@ -200,41 +200,53 @@ public static function extend($params){
 					$additionalPropName =>
 					$additionalPropValue
 				){
-					//Is the original property exists
-					$isOriginalPropExists = self::isPropExists([
-						'object' => $result,
-						'propName' => $additionalPropName
-					]);
-					//Original property value
-					$originalPropValue = self::getPropValue([
+					//Is the source property exists
+					$isSourcePropExists = self::isPropExists([
 						'object' => $result,
 						'propName' => $additionalPropName
 					]);
 					
+					if ($isSourcePropExists){
+						//Source property value
+						$sourcePropValue = self::getPropValue([
+							'object' => $result,
+							'propName' => $additionalPropName
+						]);
+						
+						//Is the source property object or array
+						$isSourcePropObjectOrArray = self::isObjectOrArray($sourcePropValue);
+					}else{
+						$sourcePropValue = null;
+						$isSourcePropObjectOrArray = false;
+					}
+					
+					//Is the additional property object or array
+					$isAdditionalPropObjectOrArray = self::isObjectOrArray($additionalPropValue);
+					
 					//The additional property value will be used by default
-					$isAdditionalUsed = true;
+					$isAdditionalPropUsed = true;
 					
 					if (
 						//Overwriting with empty value is disabled
 						!$params->overwriteWithEmpty &&
-						//And original property exists. Because if not exists we must set it in anyway (an empty value is better than nothing, right?)
-						$isOriginalPropExists
+						//And source property exists. Because if not exists we must set it in anyway (an empty value is better than nothing, right?)
+						$isSourcePropExists
 					){
 						//Check if additional property value is empty
-						$isAdditionalUsed =
+						$isAdditionalPropUsed =
 							(
+								//Empty object or array
+								(
+									$isAdditionalPropObjectOrArray &&
+									count((array) $additionalPropValue) == 0
+								) ||
 								//Empty string
 								(
 									is_string($additionalPropValue) &&
 									$additionalPropValue == ''
 								) ||
 								//NULL
-								is_null($additionalPropValue) ||
-								//Empty object or array
-								(
-									self::isObjectOrArray($additionalPropValue) &&
-									count((array) $additionalPropValue) == 0
-								)
+								is_null($additionalPropValue)
 							) ?
 							//Additional is empty — don't use it
 							false:
@@ -244,51 +256,44 @@ public static function extend($params){
 						
 						if (
 							//Additional property value is empty
-							!$isAdditionalUsed &&
-							//And original property value is empty too
+							!$isAdditionalPropUsed &&
+							//And source property value is empty too
 							(
+								//Empty object or array
+								(
+									$isSourcePropObjectOrArray &&
+									count((array) $sourcePropValue) == 0
+								) ||
 								//Empty string
 								(
-									is_string($originalPropValue) &&
-									$originalPropValue == ''
+									is_string($sourcePropValue) &&
+									$sourcePropValue == ''
 								) ||
 								//NULL
-								is_null($originalPropValue) ||
-								//Empty object or array
-								(
-									self::isObjectOrArray($originalPropValue) &&
-									count((array) $originalPropValue) == 0
-								)
+								is_null($sourcePropValue)
 							) &&
 							//But they have different types
-							$originalPropValue !== $additionalPropValue
+							$sourcePropValue !== $additionalPropValue
 						){
-							//Okay, overwrite original in this case
-							$isAdditionalUsed = true;
+							//Okay, overwrite source in this case
+							$isAdditionalPropUsed = true;
 						}
 					}
 					
 					//If additional value must be used
-					if ($isAdditionalUsed){
+					if ($isAdditionalPropUsed){
 						if (
 							//If recursive merging is needed
 							$params->deep &&
+							//And we can extend source value
+							$isSourcePropObjectOrArray &&
 							//And the value is an object or array
-							self::isObjectOrArray($additionalPropValue)
+							$isAdditionalPropObjectOrArray
 						){
-							//Init initial property value to extend
-							if (!$isOriginalPropExists){
-								$originalPropValue =
-									gettype($additionalPropValue) == 'object' ?
-									new \stdClass() :
-									[]
-								;
-							}
-							
 							//Start recursion
 							$additionalPropValue = self::extend([
 								'objects' => [
-									$originalPropValue,
+									$sourcePropValue,
 									$additionalPropValue
 								],
 								'deep' => true,