diff --git a/README.rst b/README.rst
index 581b0d4..ebd6e87 100644
--- a/README.rst
+++ b/README.rst
@@ -92,6 +92,8 @@ The backend has the following optional settings:
   See `here <http://xapian.org/docs/apidoc/html/classXapian_1_1QueryParser.html#ac7dc3b55b6083bd3ff98fc8b2726c8fd>`__ for
   more information about the different strategies.
 
+- ``XAPIAN_NGRAM_MIN_LENGTH``, ``XAPIAN_NGRAM_MAX_LENGTH``: options for custom configuration of ngrams (phrases) length.
+
 - ``HAYSTACK_XAPIAN_USE_LOCKFILE``: Use a lockfile to prevent database locking errors when running management commands with multiple workers.
   Defaults to `True`.
 
diff --git a/xapian_backend.py b/xapian_backend.py
index 03087b0..f4b740f 100755
--- a/xapian_backend.py
+++ b/xapian_backend.py
@@ -19,8 +19,8 @@ from haystack.inputs import AutoQuery
 from haystack.models import SearchResult
 from haystack.utils import get_identifier, get_model_ct
 
-NGRAM_MIN_LENGTH = 2
-NGRAM_MAX_LENGTH = 15
+NGRAM_MIN_LENGTH = getattr(settings, 'XAPIAN_NGRAM_MIN_LENGTH', 2)
+NGRAM_MAX_LENGTH = getattr(settings, 'XAPIAN_NGRAM_MAX_LENGTH', 15)
 
 LONG_TERM = re.compile(b'[^\s]{239,}')
 LONG_TERM_METHOD = getattr(settings, 'XAPIAN_LONG_TERM_METHOD', 'truncate')
@@ -134,7 +134,7 @@ class XHValueRangeProcessor(xapian.ValueRangeProcessor):
                         begin = -sys.maxsize - 1
                     elif field_type == 'float':
                         begin = float('-inf')
-                    elif field_type == 'date' or field_type == 'datetime':
+                    elif field_type in ['date', 'datetime']:
                         begin = '00010101000000'
                 elif end == '*':
                     if field_type == 'text':
@@ -143,7 +143,7 @@ class XHValueRangeProcessor(xapian.ValueRangeProcessor):
                         end = sys.maxsize
                     elif field_type == 'float':
                         end = float('inf')
-                    elif field_type == 'date' or field_type == 'datetime':
+                    elif field_type in ['date', 'datetime']:
                         end = '99990101000000'
 
                 if field_type == 'float':
@@ -1616,7 +1616,7 @@ def _term_to_xapian_value(term, field_type):
         value = INTEGER_FORMAT % term
     elif field_type == 'float':
         value = xapian.sortable_serialise(term)
-    elif field_type == 'date' or field_type == 'datetime':
+    elif field_type in ['date', 'datetime']:
         if field_type == 'date':
             # http://stackoverflow.com/a/1937636/931303 and comments
             term = datetime.datetime.combine(term, datetime.time())
@@ -1679,7 +1679,7 @@ def _from_xapian_value(value, field_type):
         return int(value)
     elif field_type == 'float':
         return xapian.sortable_unserialise(value)
-    elif field_type == 'date' or field_type == 'datetime':
+    elif field_type in ['date', 'datetime']:
         datetime_value = datetime.datetime.strptime(value, DATETIME_FORMAT)
         if field_type == 'datetime':
             return datetime_value