diff --git a/django/contrib/humanize/tests.py b/django/contrib/humanize/tests.py
index 038709fe83..f921b12778 100644
--- a/django/contrib/humanize/tests.py
+++ b/django/contrib/humanize/tests.py
@@ -53,6 +53,12 @@ class HumanizeTests(TestCase):
         with self.settings(USE_L10N=True, USE_THOUSAND_SEPARATOR=False):
             self.humanize_tester(test_list, result_list, 'intcomma')
 
+    def test_intcomma_without_number_grouping(self):
+        # Regression for #17414
+        with translation.override('ja'):
+            with self.settings(USE_L10N=True):
+                self.humanize_tester([100], ['100'], 'intcomma')
+
     def test_intword(self):
         test_list = ('100', '1000000', '1200000', '1290000',
                      '1000000000', '2000000000', '6000000000000',
diff --git a/django/utils/numberformat.py b/django/utils/numberformat.py
index c6528c0167..924d06511b 100644
--- a/django/utils/numberformat.py
+++ b/django/utils/numberformat.py
@@ -2,20 +2,21 @@ from django.conf import settings
 from django.utils.safestring import mark_safe
 
 
-def format(number, decimal_sep, decimal_pos=None, grouping=0, thousand_sep='', force_grouping=False):
+def format(number, decimal_sep, decimal_pos=None, grouping=0, thousand_sep='',
+           force_grouping=False):
     """
     Gets a number (as a number or string), and returns it as a string,
-    using formats definied as arguments:
+    using formats defined as arguments:
 
     * decimal_sep: Decimal separator symbol (for example ".")
     * decimal_pos: Number of decimal positions
     * grouping: Number of digits in every group limited by thousand separator
     * thousand_sep: Thousand separator symbol (for example ",")
-
     """
-    use_grouping = force_grouping or settings.USE_L10N and \
-        settings.USE_THOUSAND_SEPARATOR and grouping
-    # Make the common case fast:
+    use_grouping = settings.USE_L10N and settings.USE_THOUSAND_SEPARATOR
+    use_grouping = use_grouping or force_grouping
+    use_grouping = use_grouping and grouping > 0
+    # Make the common case fast
     if isinstance(number, int) and not use_grouping and not decimal_pos:
         return mark_safe(unicode(number))
     # sign
@@ -35,7 +36,8 @@ def format(number, decimal_sep, decimal_pos=None, grouping=0, thousand_sep='', f
         int_part, dec_part = str_number, ''
     if decimal_pos is not None:
         dec_part = dec_part + ('0' * (decimal_pos - len(dec_part)))
-    if dec_part: dec_part = decimal_sep + dec_part
+    if dec_part:
+        dec_part = decimal_sep + dec_part
     # grouping
     if use_grouping:
         int_part_gd = ''