diff --git a/src/Entity/Parts/PartLot.php b/src/Entity/Parts/PartLot.php
index 1bedc6bc..5ade5bc5 100644
--- a/src/Entity/Parts/PartLot.php
+++ b/src/Entity/Parts/PartLot.php
@@ -71,9 +71,9 @@ class PartLot extends DBElement
     protected $expiration_date;
 
     /**
-     * @var Storelocation The storelocation of this lot
+     * @var Storelocation|null The storelocation of this lot
      * @ORM\ManyToOne(targetEntity="Storelocation")
-     * @ORM\JoinColumn(name="id_store_location", referencedColumnName="id")
+     * @ORM\JoinColumn(name="id_store_location", referencedColumnName="id", nullable=true)
      * @Selectable()
      */
     protected $storage_location;
@@ -82,6 +82,7 @@ class PartLot extends DBElement
      * @var Part The part that is stored in this lot
      * @ORM\ManyToOne(targetEntity="Part", inversedBy="partLots")
      * @ORM\JoinColumn(name="id_part", referencedColumnName="id")
+     * @Assert\NotNull()
      */
     protected $part;
 
@@ -195,7 +196,7 @@ class PartLot extends DBElement
 
     /**
      * Gets the storage locatiion, where this part lot is stored.
-     * @return Storelocation The store location where this part is stored
+     * @return Storelocation|null The store location where this part is stored
      */
     public function getStorageLocation(): ?Storelocation
     {
@@ -204,10 +205,10 @@ class PartLot extends DBElement
 
     /**
      * Sets the storage location, where this part lot is stored
-     * @param Storelocation $storage_location
+     * @param Storelocation|null $storage_location
      * @return PartLot
      */
-    public function setStorageLocation(Storelocation $storage_location): PartLot
+    public function setStorageLocation(?Storelocation $storage_location): PartLot
     {
         $this->storage_location = $storage_location;
         return $this;
diff --git a/src/Form/Part/PartLotType.php b/src/Form/Part/PartLotType.php
index a4c1ccc0..2f4b0940 100644
--- a/src/Form/Part/PartLotType.php
+++ b/src/Form/Part/PartLotType.php
@@ -58,6 +58,7 @@ class PartLotType extends AbstractType
 
         $builder->add('storage_location', StructuralEntityType::class, ['class' => Storelocation::class,
             'label' => 'part_lot.edit.location',
+            'required' => false,
             'disable_not_selectable' => true,
             'attr' => ['class' => 'selectpicker form-control-sm', 'data-live-search' => true]]);
 
diff --git a/src/Migrations/Version20190812154222.php b/src/Migrations/Version20190812154222.php
index dfe2f63f..e5055dd4 100644
--- a/src/Migrations/Version20190812154222.php
+++ b/src/Migrations/Version20190812154222.php
@@ -32,14 +32,14 @@ final class Version20190812154222 extends AbstractMigration
         $this->addSql(
             'INSERT INTO part_lots (id_part, id_store_location, amount, instock_unknown, last_modified, datetime_added) ' .
                 'SELECT parts.id, parts.id_storelocation,  parts.instock, 0, NOW(), NOW() FROM parts ' .
-                'WHERE parts.instock >= 0 AND parts.id_storelocation IS NOT NULL'
+                'WHERE parts.instock >= 0'
         );
 
         //Migrate part locations for parts with unknown instock
         $this->addSql(
             'INSERT INTO part_lots (id_part, id_store_location, amount, instock_unknown, last_modified, datetime_added) ' .
             'SELECT parts.id, parts.id_storelocation, 0, 1, NOW(), NOW() FROM parts ' .
-            'WHERE parts.instock = -2 AND parts.id_storelocation IS NOT NULL'
+            'WHERE parts.instock = -2'
         );
 
         $this->addSql('ALTER TABLE attachements CHANGE element_id element_id INT DEFAULT NULL, CHANGE type_id type_id INT DEFAULT NULL, CHANGE last_modified last_modified DATETIME NOT NULL, CHANGE datetime_added datetime_added DATETIME NOT NULL');
diff --git a/templates/Parts/info/_part_lots.html.twig b/templates/Parts/info/_part_lots.html.twig
index 853dbf56..d7470a74 100644
--- a/templates/Parts/info/_part_lots.html.twig
+++ b/templates/Parts/info/_part_lots.html.twig
@@ -14,7 +14,13 @@
         <tr>
             <td>{{ lot.description }}</td>
             <td>
-                {{ lot.storageLocation.fullPath }}
+                {% if lot.storageLocation %}
+                    {{ lot.storageLocation.fullPath }}
+                {% else %}
+                    <span class="badge badge-pill badge-warning">
+                        <i class="fas fa-question-circle fa-fw"></i> {% trans %}part_lots.location_unknown{% endtrans %}
+                    </span>
+                {% endif %}
             </td>
             <td>
                 {% if lot.instockUnknown %}