diff --git a/src/Forms/SingleSelectField.php b/src/Forms/SingleSelectField.php
index 7fad88036..8c60a84cf 100644
--- a/src/Forms/SingleSelectField.php
+++ b/src/Forms/SingleSelectField.php
@@ -124,15 +124,17 @@ abstract class SingleSelectField extends SelectField
     {
         // Check if valid value is given
         $selected = $this->Value();
+        $validValues = $this->getValidValues();
+
         if (strlen($selected)) {
             // Use selection rules to check which are valid
-            foreach ($this->getValidValues() as $formValue) {
+            foreach ($validValues as $formValue) {
                 if ($this->isSelectedValue($formValue, $selected)) {
                     return true;
                 }
             }
         } else {
-            if ($this->getHasEmptyDefault()) {
+            if ($this->getHasEmptyDefault() || !$validValues || in_array('', $validValues)) {
                 // Check empty value
                 return true;
             }
diff --git a/tests/php/Forms/DropdownFieldTest.php b/tests/php/Forms/DropdownFieldTest.php
index 585287a11..8aaa8fed4 100644
--- a/tests/php/Forms/DropdownFieldTest.php
+++ b/tests/php/Forms/DropdownFieldTest.php
@@ -505,7 +505,7 @@ class DropdownFieldTest extends SapphireTest
      */
     public function testRequiredDropdownHasEmptyDefault()
     {
-        $field = new \SilverStripe\Forms\DropdownField("RequiredField", "dropdown", ["item 1", "item 2"]);
+        $field = new DropdownField("RequiredField", "dropdown", ["item 1", "item 2"]);
 
         $form = new Form(
             Controller::curr(),
@@ -517,4 +517,33 @@ class DropdownFieldTest extends SapphireTest
 
         $this->assertTrue($field->getHasEmptyDefault());
     }
+
+    public function testEmptySourceDoesntBlockValidation()
+    {
+        // Empty source
+        $field = new DropdownField("EmptySource", "", []);
+        $v = new RequiredFields();
+        $field->validate($v);
+        $this->assertTrue($v->getResult()->isValid());
+
+        // Source with a setEmptyString
+        $field = new DropdownField("EmptySource", "", []);
+        $field->setEmptyString('(Select one)');
+        $v = new RequiredFields();
+        $field->validate($v);
+        $this->assertTrue($v->getResult()->isValid());
+
+        // Source with an empty value
+        $field = new DropdownField("SourceWithBlankVal", "", [ "" => "(Choose)" ]);
+        $v = new RequiredFields();
+        $field->validate($v);
+        $this->assertTrue($v->getResult()->isValid());
+
+        // Source with all items disabled
+        $field = new DropdownField("SourceWithBlankVal", "", [ "A" => "A", "B" => "B" ]);
+        $field->setDisabledItems([ 'A', 'B' ]);
+        $v = new RequiredFields();
+        $field->validate($v);
+        $this->assertTrue($v->getResult()->isValid());
+    }
 }