diff --git a/README.rst b/README.rst
index 142f4c60a..7a52cb7bc 100644
--- a/README.rst
+++ b/README.rst
@@ -477,17 +477,33 @@ setter methods by setting ``$bIgnoreVisibility`` to true:
 Simple types instead of objects
 ===============================
 When a variable's type is a class and JSON data is a simple type
-like ``string``, JsonMapper passes this value to the class' constructor.
-
-If you do not want this, set ``$bStrictObjectTypeChecking`` to ``true``:
+like ``string``, JsonMapper can pass this value to the class' constructor
+when configured to do so:
 
 .. code:: php
 
     $jm = new JsonMapper();
-    $jm->bStrictObjectTypeChecking = true;
+    $jm->bStrictObjectTypeChecking = false;
     $jm->map(...);
 
-An exception is then thrown in such cases.
+This can be used to automatically initialize DateTime objects
+from date strings.
+
+Disabling this strict object type checks may lead to problems, though:
+
+- When a class does not have a constructor or no constructor parameter,
+  the value will get lost
+- When the constructor has more than 1 required parameter, it will crash.
+- When the constructor's parameter type does not match the one of the
+  data in JSON, it will crash
+- ``@required`` properties will not be filled
+
+.. note::
+   The default value changed from ``false`` to ``true`` in version 5 to
+   increase security.
+
+   Now you have to opt in if you want to pass simple types to
+   the class constructor.
 
 
 Passing arrays to ``map()``
diff --git a/src/JsonMapper.php b/src/JsonMapper.php
index 7d0bb4457..08d7178d4 100644
--- a/src/JsonMapper.php
+++ b/src/JsonMapper.php
@@ -64,7 +64,7 @@ class JsonMapper
      *
      * @var boolean
      */
-    public $bStrictObjectTypeChecking = false;
+    public $bStrictObjectTypeChecking = true;
 
     /**
      * Throw an exception, if null value is found
diff --git a/tests/ArrayTest.php b/tests/ArrayTest.php
index c0511bc41..bf2e99100 100644
--- a/tests/ArrayTest.php
+++ b/tests/ArrayTest.php
@@ -48,6 +48,7 @@ public function testMapTypedArray()
     public function testMapTypedSimpleArray()
     {
         $jm = new JsonMapper();
+        $jm->bStrictObjectTypeChecking = false;
         $jm->bStrictNullTypesInArrays = false;
         $sn = $jm->map(
             json_decode('{"typedSimpleArray":["2014-01-02",null,"2014-05-07"]}'),
@@ -510,6 +511,7 @@ public function testMapArrayStrangeKeys()
     public function testMapTypedSimpleArrayFromObject()
     {
         $jm = new JsonMapper();
+        $jm->bStrictObjectTypeChecking = false;
         $sn = $jm->map(
             json_decode('{"typedSimpleArray":{"en-US":"2014-01-02"}}'),
             new JsonMapperTest_Array()
@@ -587,6 +589,7 @@ public function testMapArrayFromVariadicFunctionWithSimpleType()
     public function testMapArrayFromVariadicFunctionWithObjectType()
     {
         $jm = new JsonMapper();
+        $jm->bStrictObjectTypeChecking = false;
         /** @var JsonMapperTest_VariadicArray $sn */
         $sn = $jm->map(
             json_decode('{"variadicDateTime":["2014-01-02","2014-05-07"]}'),
diff --git a/tests/ClassMapTest.php b/tests/ClassMapTest.php
index 511eeb3c4..e9d9a4195 100644
--- a/tests/ClassMapTest.php
+++ b/tests/ClassMapTest.php
@@ -59,6 +59,7 @@ public static function classMapTestData()
     public function testClassMap($classMapValue)
     {
         $jm = new JsonMapper();
+        $jm->bStrictObjectTypeChecking = false;
         $jm->classMap[self::CLASS_MAP_CLASS] = $classMapValue;
         $sn = $jm->map(
             json_decode('{"pPlainObject":"'.self::CLASS_MAP_DATA.'"}'),
@@ -75,6 +76,7 @@ public function testClassMap($classMapValue)
     public function testNamespaceKeyWithLeadingBackslash()
     {
         $jm = new JsonMapper();
+        $jm->bStrictObjectTypeChecking = false;
         $jm->classMap['\\namespacetest\\model\\User']
             = \namespacetest\Unit::class;
         $data = $jm->map(
@@ -88,6 +90,7 @@ public function testNamespaceKeyWithLeadingBackslash()
     public function testNamespaceKeyNoLeadingBackslash()
     {
         $jm = new JsonMapper();
+        $jm->bStrictObjectTypeChecking = false;
         $jm->classMap[\namespacetest\model\User::class]
             = \namespacetest\Unit::class;
         $data = $jm->map(
diff --git a/tests/Enums_PHP81_Test.php b/tests/Enums_PHP81_Test.php
index 2f15d79ea..deb320d66 100644
--- a/tests/Enums_PHP81_Test.php
+++ b/tests/Enums_PHP81_Test.php
@@ -22,6 +22,7 @@ class Enums_PHP81_Test extends \PHPUnit\Framework\TestCase
     public function testEnumMapping()
     {
         $jm = new JsonMapper();
+        $jm->bStrictObjectTypeChecking = false;
         /** @var \Enums\ObjectWithEnum $sn */
         $sn = $jm->map(
             json_decode(self::TEST_DATA),
diff --git a/tests/NamespaceTest.php b/tests/NamespaceTest.php
index f6bc5d2a2..d97ea5122 100644
--- a/tests/NamespaceTest.php
+++ b/tests/NamespaceTest.php
@@ -53,6 +53,7 @@ public function testMapChildClassNamespace()
     public function testMapChildClassConstructorNamespace()
     {
         $mapper = new \JsonMapper();
+        $mapper->bStrictObjectTypeChecking = false;
         $json = '{"user":"John Smith"}';
         $res = $mapper->map(json_decode($json), new UnitData());
         $this->assertInstanceOf(\namespacetest\UnitData::class, $res);
@@ -106,6 +107,7 @@ public function testMapCustomArrayObject()
     public function testSetterNamespacedTypeHint()
     {
         $mapper = new \JsonMapper();
+        $mapper->bStrictObjectTypeChecking = false;
         $json = '{"namespacedTypeHint":"Foo"}';
         $res = $mapper->map(json_decode($json), new UnitData());
         $this->assertInstanceOf(\namespacetest\UnitData::class, $res);
diff --git a/tests/ObjectTest.php b/tests/ObjectTest.php
index 260ae55c0..fa3341f71 100644
--- a/tests/ObjectTest.php
+++ b/tests/ObjectTest.php
@@ -52,6 +52,7 @@ public function testMapObjectByClassName()
     public function testMapDateTime()
     {
         $jm = new JsonMapper();
+        $jm->bStrictObjectTypeChecking = false;
         $sn = $jm->map(
             json_decode('{"datetime":"2014-04-01T00:00:00+02:00"}'),
             new JsonMapperTest_Object()