diff --git a/InvenTree/part/models.py b/InvenTree/part/models.py
index 4730ba1e9c..ea26e5e5c7 100644
--- a/InvenTree/part/models.py
+++ b/InvenTree/part/models.py
@@ -1083,7 +1083,9 @@ class Part(MPTTModel):
             parts: Set of parts already found (to prevent recursion issues)
         """
 
-        for bom_item in self.bom_items.all().select_related('sub_part'):
+        items = self.bom_items.all().prefetch_related('sub_part')
+
+        for bom_item in items:
 
             sub_part = bom_item.sub_part
 
@@ -1885,25 +1887,27 @@ class BomItem(models.Model):
         - If the "sub_part" is trackable, then the "part" must be trackable too!
         """
 
-        # If the sub_part is 'trackable' then the 'quantity' field must be an integer
         try:
-            if self.sub_part.trackable:
-                if not self.quantity == int(self.quantity):
-                    raise ValidationError({
-                        "quantity": _("Quantity must be integer value for trackable parts")
-                    })
-
-                # Force the upstream part to be trackable if the sub_part is trackable
-                if not self.part.trackable:
-                    self.part.trackable = True
-                    self.part.clean()
-                    self.part.save()
+            # Check for circular BOM references
+            if self.sub_part:
+                self.sub_part.checkAddToBOM(self.part)
+                
+                # If the sub_part is 'trackable' then the 'quantity' field must be an integer
+                if self.sub_part.trackable:
+                    if not self.quantity == int(self.quantity):
+                        raise ValidationError({
+                            "quantity": _("Quantity must be integer value for trackable parts")
+                        })
 
+                    # Force the upstream part to be trackable if the sub_part is trackable
+                    if not self.part.trackable:
+                        self.part.trackable = True
+                        self.part.clean()
+                        self.part.save()
+            else:
+                raise ValidationError({'sub_part': _('Sub part must be specified')})
         except Part.DoesNotExist:
-            pass
-
-        # Check for circular BOM references
-        self.sub_part.checkAddToBOM(self.part)
+            raise ValidationError({'sub_part': _('Sub part must be specified')})
 
     class Meta:
         verbose_name = _("BOM Item")
diff --git a/InvenTree/part/views.py b/InvenTree/part/views.py
index e2f03b89b8..ac4925685f 100644
--- a/InvenTree/part/views.py
+++ b/InvenTree/part/views.py
@@ -2428,30 +2428,34 @@ class BomItemCreate(AjaxCreateView):
 
         part_id = form['part'].value()
 
+        # Construct a queryset for the part field
+        part_query = Part.objects.filter(active=True)
+
+        # Construct a queryset for the sub_part field
+        sub_part_query = Part.objects.filter(
+            component=True,
+            active=True
+        )
+
         try:
             part = Part.objects.get(id=part_id)
-
-            # Only allow active parts to be selected
-            query = form.fields['part'].queryset.filter(active=True)
-            form.fields['part'].queryset = query
-
-            # Don't allow selection of sub_part objects which are already added to the Bom!
-            query = form.fields['sub_part'].queryset
             
-            # Don't allow a part to be added to its own BOM
-            query = query.exclude(id=part.id)
-            query = query.filter(active=True)
+            # Hide the 'part' field
+            form.fields['part'].widget = HiddenInput()
+
+            # Exclude the part from its own BOM
+            sub_part_query = sub_part_query.exclude(id=part.id)
             
             # Eliminate any options that are already in the BOM!
-            query = query.exclude(id__in=[item.id for item in part.getRequiredParts()])
-            
-            form.fields['sub_part'].queryset = query
-
-            form.fields['part'].widget = HiddenInput()
+            sub_part_query = sub_part_query.exclude(id__in=[item.id for item in part.getRequiredParts()])
 
         except (ValueError, Part.DoesNotExist):
             pass
 
+        # Set the querysets for the fields
+        form.fields['part'].queryset = part_query
+        form.fields['sub_part'].queryset = sub_part_query
+
         return form
 
     def get_initial(self):
@@ -2492,6 +2496,8 @@ class BomItemEdit(AjaxUpdateView):
         - Remove any part items that are already in the BOM
         """
 
+        item = self.get_object()
+
         form = super().get_form()
 
         part_id = form['part'].value()
@@ -2499,9 +2505,14 @@ class BomItemEdit(AjaxUpdateView):
         try:
             part = Part.objects.get(pk=part_id)
 
-            query = form.fields['sub_part'].queryset
+            # Construct a queryset
+            query = Part.objects.filter(component=True)
 
-            # Reduce the available selection options
+            # Limit to "active" items, *unless* the currently selected item is not active
+            if item.sub_part.active:
+                query = query.filter(active=True)
+
+            # Prevent the parent part from being selected
             query = query.exclude(pk=part_id)
 
             # Eliminate any options that are already in the BOM,