diff --git a/libraries/src/Form/Field/AccessiblemediaField.php b/libraries/src/Form/Field/AccessiblemediaField.php
index 526edc67c6968..aade4cd71e6f5 100644
--- a/libraries/src/Form/Field/AccessiblemediaField.php
+++ b/libraries/src/Form/Field/AccessiblemediaField.php
@@ -130,25 +130,40 @@ public function __set($name, $value)
 	 */
 	public function setup(\SimpleXMLElement $element, $value, $group = null)
 	{
-		json_decode($value);
-
-		// Check if value is a valid JSON string.
-		if ($value !== '' && json_last_error() !== JSON_ERROR_NONE)
+		/**
+		 * If the value is not a string, it is
+		 * most likely within a custom field of type subform
+		 * and the value is a stdClass with properties
+		 * imagefile and alt_text. So it is fine.
+		*/
+		if (\is_string($value))
 		{
-			/**
-			* If the value is not empty and is not a valid JSON string,
-			* it is most likely a custom field created in Joomla 3 and
-			* the value is a string that contains the file name.
-			*/
-			if (file_exists(JPATH_ROOT . '/' . $value))
-			{
-				$value = '{"imagefile":"' . $value . '","alt_text":""}';
-			}
-			else
+			json_decode($value);
+
+			// Check if value is a valid JSON string.
+			if ($value !== '' && json_last_error() !== JSON_ERROR_NONE)
 			{
-				$value = '';
+				/**
+				 * If the value is not empty and is not a valid JSON string,
+				 * it is most likely a custom field created in Joomla 3 and
+				 * the value is a string that contains the file name.
+				*/
+				if (file_exists(JPATH_ROOT . '/' . $value))
+				{
+					$value = '{"imagefile":"' . $value . '","alt_text":""}';
+				}
+				else
+				{
+					$value = '';
+				}
 			}
 		}
+		elseif (!is_object($value)
+			|| !property_exists($value, 'imagefile')
+			|| !property_exists($value, 'alt_text'))
+		{
+			return false;
+		}
 
 		if (!parent::setup($element, $value, $group))
 		{
diff --git a/plugins/fields/media/media.php b/plugins/fields/media/media.php
index c1b10da4016e1..e47d47a1cf9b3 100644
--- a/plugins/fields/media/media.php
+++ b/plugins/fields/media/media.php
@@ -63,7 +63,7 @@ public function onCustomFieldsBeforePrepareField($context, $item, $field)
 		}
 
 		// Check if the field value is an old (string) value
-		$field->apivalue = $this->checkValue($field->value);
+		$field->value = $this->checkValue($field->value);
 	}
 
 	/**
diff --git a/plugins/fields/media/tmpl/media.php b/plugins/fields/media/tmpl/media.php
index 53c8015ac0ecf..a9ef2b447ba19 100644
--- a/plugins/fields/media/tmpl/media.php
+++ b/plugins/fields/media/tmpl/media.php
@@ -20,7 +20,8 @@
 	$class = ' class="' . htmlentities($class, ENT_COMPAT, 'UTF-8', true) . '"';
 }
 
-$value  = $field->apivalue;
+$value  = $field->value;
+
 $buffer = '';
 
 if ($value)
diff --git a/tests/Unit/Libraries/Cms/Form/Field/AccessiblemediaFieldTest.php b/tests/Unit/Libraries/Cms/Form/Field/AccessiblemediaFieldTest.php
index caa12baf98124..f8a7e1c9fd2ec 100644
--- a/tests/Unit/Libraries/Cms/Form/Field/AccessiblemediaFieldTest.php
+++ b/tests/Unit/Libraries/Cms/Form/Field/AccessiblemediaFieldTest.php
@@ -190,6 +190,56 @@ public function testSetupWithValueThatIsNotValid()
 		$this->assertEquals('', $accessiblemediafield->__get('value'));
 	}
 
+	/**
+	 * Tests method to attach a Form object to the field.
+	 * If the value is a stdClass that is valid.
+	 * This does change nothing. The value should be the same than before.
+
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testSetupWithValueThatIsValidStdclass()
+	{
+		$accessiblemediafield = $this->createAccessiblemediaField();
+
+		$obj = new \stdClass;
+		$obj->imagefile = '/images/joomla_black.png';
+		$obj->alt_text = 'some alt text';
+
+		$element = new \SimpleXMLElement('<field name="testfield" />');
+
+		$this->assertTrue($accessiblemediafield->setup($element, $obj, null));
+		$this->assertEquals($obj, $accessiblemediafield->__get('value'));
+	}
+
+	/**
+	 * Tests method to attach a Form object to the field.
+	 * If the value is a stdClass that is not valid for the accessible media field.
+	 * This does change in the setup method. Result is false.
+
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testSetupWithValueThatIsNoValidStdclass()
+	{
+		$accessiblemediafield = $this->createAccessiblemediaField();
+
+		$obj1 = new \stdClass;
+		$obj2 = new \stdClass;
+		$obj3 = new \stdClass;
+
+		$obj1->imagefile = '/images/joomla_black.png';
+		$obj2->alt_text = 'some alt text';
+
+		$element = new \SimpleXMLElement('<field name="testfield" />');
+
+		$this->assertFalse($accessiblemediafield->setup($element, $obj1, null));
+		$this->assertFalse($accessiblemediafield->setup($element, $obj2, null));
+		$this->assertFalse($accessiblemediafield->setup($element, $obj3, null));
+	}
+
 	/**
 	 * Tests method to attach a Form object to the field.
 	 * If the SimpleXMLElement is not of the field type, the setup method returns false.