diff --git a/mongoengine/fields.py b/mongoengine/fields.py
index 670e3cd3..bd81d3a8 100644
--- a/mongoengine/fields.py
+++ b/mongoengine/fields.py
@@ -66,6 +66,9 @@ class StringField(BaseField):
                 regex = r'%s$'
             elif op == 'exact':
                 regex = r'^%s$'
+            
+            # escape unsafe characters which could lead to a re.error
+            value = re.escape(value)
             value = re.compile(regex % value, flags)
         return value
 
diff --git a/tests/queryset.py b/tests/queryset.py
index 8cbd9a40..1efd034c 100644
--- a/tests/queryset.py
+++ b/tests/queryset.py
@@ -288,6 +288,13 @@ class QuerySetTest(unittest.TestCase):
         self.assertEqual(obj, person)
         obj = self.Person.objects(Q(name__iexact='gUIDO VAN rOSSU')).first()
         self.assertEqual(obj, None)
+        
+        # Test unsafe expressions
+        person = self.Person(name='Guido van Rossum [.\'Geek\']')
+        person.save()
+
+        obj = self.Person.objects(Q(name__icontains='[.\'Geek')).first()
+        self.assertEqual(obj, person)
 
     def test_filter_chaining(self):
         """Ensure filters can be chained together.