diff --git a/lib/liquid/standardfilters.rb b/lib/liquid/standardfilters.rb
index 90dfdd3a..50f2dc40 100644
--- a/lib/liquid/standardfilters.rb
+++ b/lib/liquid/standardfilters.rb
@@ -76,7 +76,7 @@ module Liquid
       words = Utils.to_integer(words)
       l = words - 1
       l = 0 if l < 0
-      wordlist.length > l ? wordlist[0..l].join(" ".freeze) + truncate_string : input
+      wordlist.length > l ? wordlist[0..l].join(" ".freeze) + truncate_string.to_s : input
     end
 
     # Split input string into an array of substrings separated by given pattern.
diff --git a/test/integration/standard_filter_test.rb b/test/integration/standard_filter_test.rb
index a20e1c39..909ad443 100644
--- a/test/integration/standard_filter_test.rb
+++ b/test/integration/standard_filter_test.rb
@@ -154,6 +154,7 @@ class StandardFiltersTest < Minitest::Test
     assert_equal 'one two three', @filters.truncatewords('one two three')
     assert_equal 'Two small (13&#8221; x 5.5&#8221; x 10&#8221; high) baskets fit inside one large basket (13&#8221;...', @filters.truncatewords('Two small (13&#8221; x 5.5&#8221; x 10&#8221; high) baskets fit inside one large basket (13&#8221; x 16&#8221; x 10.5&#8221; high) with cover.', 15)
     assert_equal "测试测试测试测试", @filters.truncatewords('测试测试测试测试', 5)
+    assert_equal 'one two1', @filters.truncatewords("one two three", 2, 1)
   end
 
   def test_strip_html