diff --git a/src/Form/Type/SIUnitType.php b/src/Form/Type/SIUnitType.php
index 3a848396..a22ba234 100644
--- a/src/Form/Type/SIUnitType.php
+++ b/src/Form/Type/SIUnitType.php
@@ -160,7 +160,7 @@ class SIUnitType extends AbstractType implements DataMapperInterface
             return null;
         }
 
-        $data = $this->si_formatter->convertValue($viewData);
+        $data = $this->si_formatter->convertValue((float) $viewData);
 
         if (isset($forms['prefix'])) {
             $forms['value']->setData($data['value']);
diff --git a/src/Services/Attachments/AttachmentManager.php b/src/Services/Attachments/AttachmentManager.php
index e898db0e..ffaac0d5 100644
--- a/src/Services/Attachments/AttachmentManager.php
+++ b/src/Services/Attachments/AttachmentManager.php
@@ -105,7 +105,13 @@ class AttachmentManager
             return false;
         }
 
-        return file_exists($this->toAbsoluteFilePath($attachment)) || $attachment->isExternal();
+        $absolute_path = $this->toAbsoluteFilePath($attachment);
+
+        if ($absolute_path === null) {
+            return false;
+        }
+
+        return file_exists($absolute_path) || $attachment->isExternal();
     }
 
     /**