diff --git a/src/Field.php b/src/Field.php
index 3bebbe4cfa..e3f938eebf 100644
--- a/src/Field.php
+++ b/src/Field.php
@@ -164,7 +164,7 @@ public function __construct()
             $value = $persistence->typecastLoadField($this, $value);
 
             if ($value === null) {
-                if ($this->required/* known bug, see https://github.com/atk4/data/issues/575, fix in https://github.com/atk4/data/issues/576 || $this->mandatory*/) {
+                if ($this->required || $this->mandatory) {
                     throw new Exception('Must not be null');
                 }
 
diff --git a/src/Persistence.php b/src/Persistence.php
index a25fe6751b..81cff1a3d0 100644
--- a/src/Persistence.php
+++ b/src/Persistence.php
@@ -179,14 +179,7 @@ public function typecastSaveRow(Model $model, array $row): array
 
             $field = $model->getField($fieldName);
 
-            $value = $this->typecastSaveField($field, $value);
-
-            // check null values for mandatory fields
-            if ($value === null && $field->mandatory) {
-                throw new ValidationException([$field->short_name => 'Mandatory field value cannot be null'], $field->getOwner());
-            }
-
-            $result[$field->getPersistenceName()] = $value;
+            $result[$field->getPersistenceName()] = $this->typecastSaveField($field, $value);
         }
 
         return $result;
diff --git a/tests/FieldTest.php b/tests/FieldTest.php
index a81f4e28aa..e6f553741b 100644
--- a/tests/FieldTest.php
+++ b/tests/FieldTest.php
@@ -65,11 +65,8 @@ public function testMandatory1(): void
         $m->set('foo', 'abc');
         $m->set('foo', '');
 
-        /* known bug, see https://github.com/atk4/data/issues/575, fix in https://github.com/atk4/data/issues/576
-        $this->expectException(ValidationException::class);*/
+        $this->expectException(ValidationException::class);
         $m->set('foo', null);
-
-        $this->assertTrue(true); // no exceptions
     }
 
     public function testRequired1(): void
diff --git a/tests/Util/DeepCopyTest.php b/tests/Util/DeepCopyTest.php
index 71babd6a63..719296adc5 100644
--- a/tests/Util/DeepCopyTest.php
+++ b/tests/Util/DeepCopyTest.php
@@ -332,7 +332,6 @@ public function testDeepError(): void
         $dc = new DeepCopy();
 
         $this->expectException(DeepCopyException::class);
-
         try {
             $invoice = $dc
                 ->from($quote)
@@ -340,8 +339,8 @@ public function testDeepError(): void
                 ->to($invoice)
                 ->with(['Lines'])
                 ->copy();
-        } catch (\Atk4\Data\Util\DeepCopyException $e) {
-            $this->assertSame('Mandatory field value cannot be null', $e->getPrevious()->getMessage());
+        } catch (DeepCopyException $e) {
+            $this->assertSame('Must not be null', $e->getPrevious()->getMessage());
 
             throw $e;
         }