diff --git a/typo3/sysext/backend/Classes/Form/Element/InputTextElement.php b/typo3/sysext/backend/Classes/Form/Element/InputTextElement.php
index 79196ef44cc670f28c392dd0c62bd333b05391af..1c67c6c926f7cf9814fba235f74e4d46d981cad5 100644
--- a/typo3/sysext/backend/Classes/Form/Element/InputTextElement.php
+++ b/typo3/sysext/backend/Classes/Form/Element/InputTextElement.php
@@ -148,10 +148,10 @@ class InputTextElement extends AbstractFormElement
             $fieldChangeFunc = $parameterArray['fieldChangeFunc'];
             if ($mode === 'append') {
                 $assignValue = 'document.querySelectorAll(' . GeneralUtility::quoteJSvalue('[data-formengine-input-name="' . $itemName . '"]') . ')[0]'
-                    . '.value=\'\'+this.options[this.selectedIndex].value+document.editform[' . GeneralUtility::quoteJSvalue($itemName) . '].value';
+                    . '.value+=\'\'+this.options[this.selectedIndex].value';
             } elseif ($mode === 'prepend') {
                 $assignValue = 'document.querySelectorAll(' . GeneralUtility::quoteJSvalue('[data-formengine-input-name="' . $itemName . '"]') . ')[0]'
-                    . '.value+=\'\'+this.options[this.selectedIndex].value';
+                    . '.value=\'\'+this.options[this.selectedIndex].value+document.editform[' . GeneralUtility::quoteJSvalue($itemName) . '].value';
             } else {
                 $assignValue = 'document.querySelectorAll(' . GeneralUtility::quoteJSvalue('[data-formengine-input-name="' . $itemName . '"]') . ')[0]'
                     . '.value=this.options[this.selectedIndex].value';