diff --git a/actionpack/lib/action_view/helpers/number_helper.rb b/actionpack/lib/action_view/helpers/number_helper.rb
index 4dafb7739a..fe0288521f 100644
--- a/actionpack/lib/action_view/helpers/number_helper.rb
+++ b/actionpack/lib/action_view/helpers/number_helper.rb
@@ -211,7 +211,7 @@ module ActionView
         defaults = I18n.translate(:'number.format', :locale => options[:locale], :default => {})
         options = options.reverse_merge(defaults)
 
-        parts = number.to_s.split('.')
+        parts = number.to_s.to_str.split('.')
         parts[0].gsub!(/(\d)(?=(\d\d\d)+(?!\d))/, "\\1#{options[:delimiter]}")
         parts.join(options[:separator]).html_safe
 
diff --git a/actionpack/test/template/number_helper_test.rb b/actionpack/test/template/number_helper_test.rb
index 0104c20bc7..0e3475d98b 100644
--- a/actionpack/test/template/number_helper_test.rb
+++ b/actionpack/test/template/number_helper_test.rb
@@ -283,33 +283,40 @@ class NumberHelperTest < ActionView::TestCase
     assert number_to_human(1).html_safe?
     assert !number_to_human("<script></script>").html_safe?
     assert number_to_human("asdf".html_safe).html_safe?
+    assert number_to_human("1".html_safe).html_safe?
 
     assert number_to_human_size(1).html_safe?
     assert number_to_human_size(1000000).html_safe?
     assert !number_to_human_size("<script></script>").html_safe?
     assert number_to_human_size("asdf".html_safe).html_safe?
+    assert number_to_human_size("1".html_safe).html_safe?
 
     assert number_with_precision(1, :strip_insignificant_zeros => false).html_safe?
     assert number_with_precision(1, :strip_insignificant_zeros => true).html_safe?
     assert !number_with_precision("<script></script>").html_safe?
     assert number_with_precision("asdf".html_safe).html_safe?
+    assert number_with_precision("1".html_safe).html_safe?
 
     assert number_to_currency(1).html_safe?
     assert !number_to_currency("<script></script>").html_safe?
     assert number_to_currency("asdf".html_safe).html_safe?
+    assert number_to_currency("1".html_safe).html_safe?
 
     assert number_to_percentage(1).html_safe?
     assert !number_to_percentage("<script></script>").html_safe?
     assert number_to_percentage("asdf".html_safe).html_safe?
+    assert number_to_percentage("1".html_safe).html_safe?
 
     assert number_to_phone(1).html_safe?
     assert_equal "&lt;script&gt;&lt;/script&gt;", number_to_phone("<script></script>")
     assert number_to_phone("<script></script>").html_safe?
     assert number_to_phone("asdf".html_safe).html_safe?
+    assert number_to_phone("1".html_safe).html_safe?
 
     assert number_with_delimiter(1).html_safe?
     assert !number_with_delimiter("<script></script>").html_safe?
     assert number_with_delimiter("asdf".html_safe).html_safe?
+    assert number_with_delimiter("1".html_safe).html_safe?
   end
 
   def test_number_helpers_should_raise_error_if_invalid_when_specified