diff --git a/humanfriendly/tests.py b/humanfriendly/tests.py
index 72dad99..e83727e 100644
--- a/humanfriendly/tests.py
+++ b/humanfriendly/tests.py
@@ -733,6 +733,10 @@ def test_concatenate(self):
         # Test the 'conjunction' option.
         assert concatenate(['one', 'two', 'three'], conjunction='or') == 'one, two or three'
         # Test the 'serial_comma' option.
+        assert concatenate([], serial_comma=True) == ''
+        assert concatenate(['one'], serial_comma=True) == 'one'
+        assert concatenate(['one', 'two'], serial_comma=True) == 'one and two'
+        assert concatenate(iter(['one', 'two']), conjunction='or', serial_comma=True) == 'one or two'
         assert concatenate(['one', 'two', 'three'], serial_comma=True) == 'one, two, and three'
 
     def test_split(self):
diff --git a/humanfriendly/text.py b/humanfriendly/text.py
index a257a6a..2f30efe 100644
--- a/humanfriendly/text.py
+++ b/humanfriendly/text.py
@@ -125,7 +125,7 @@ def concatenate(items, conjunction='and', serial_comma=False):
     if len(items) > 1:
         final_item = items.pop()
         formatted = ', '.join(items)
-        if serial_comma:
+        if serial_comma and len(items) > 1:
             formatted += ','
         return ' '.join([formatted, conjunction, final_item])
     elif items: