diff --git a/scrapy/loader/__init__.py b/scrapy/loader/__init__.py
index a7c75a46aab..7c7f6686669 100644
--- a/scrapy/loader/__init__.py
+++ b/scrapy/loader/__init__.py
@@ -35,6 +35,9 @@ def __init__(self, item=None, selector=None, response=None, parent=None, **conte
         self.parent = parent
         self._local_item = context['item'] = item
         self._local_values = defaultdict(list)
+        # Preprocess values if item built from dict
+        for field_name, value in item.items():
+            self._values[field_name] = self._process_input_value(field_name, value)
 
     @property
     def _values(self):