diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8ab8beb8..0e5cbc3d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Fixed
 
+- Fix empty dropdown value (-1) on form submission
 - Fix text area fields size and alignment
 - Optimize container loading when there are a large number of entities
 
diff --git a/inc/destinationfield.class.php b/inc/destinationfield.class.php
index 831f2081..3cc553cc 100644
--- a/inc/destinationfield.class.php
+++ b/inc/destinationfield.class.php
@@ -135,7 +135,8 @@ public function applyConfiguratedValueToInputUsingAnswers(
                     $input[sprintf('itemtype_%s', $field_name)] = $answer->getRawAnswer()['itemtype'];
                     $input[sprintf('items_id_%s', $field_name)] = $answer->getRawAnswer()['items_id'];
                 } elseif ($field->fields['type'] == 'dropdown') {
-                    $input[$field_name] = $answer->getRawAnswer()['items_id'];
+                    $raw_id = (int) $answer->getRawAnswer()['items_id'];
+                    $input[$field_name] = ($raw_id > 0) ? $raw_id : null;
                 } else {
                     $input[$field_name] = $value ?? $answer->getRawAnswer();
                 }