diff --git a/src/Form/StringTranslationUiAddForm.php b/src/Form/StringTranslationUiAddForm.php
index c510d9c..9b7cee3 100644
--- a/src/Form/StringTranslationUiAddForm.php
+++ b/src/Form/StringTranslationUiAddForm.php
@@ -137,6 +137,18 @@ class StringTranslationUiAddForm extends ConfigFormBase {
       $form_state->setErrorByName('context', $this->t('The context must contain only lowercase letters, numbers, and underscores.'));
     }
 
+    $strings = $form_state->getValue('strings');
+
+    $stringsToTranslate = $this->getStringsToTranslate($strings);
+
+    foreach ($stringsToTranslate as $key => $string) {
+
+      if (ctype_digit($string)) {
+        $form_state->setErrorByName('strings', $this->t('This string: @current_string is invalid. We can\'t translate numbers', ['@current_string' => $string]));
+        return FALSE;
+      }
+
+    }
   }
 
   /**