diff --git a/lib/capybara/selector/css.rb b/lib/capybara/selector/css.rb
index c90cdce6..4cead1bf 100644
--- a/lib/capybara/selector/css.rb
+++ b/lib/capybara/selector/css.rb
@@ -30,7 +30,7 @@ module Capybara
       class Splitter
         def split(css)
           selectors = []
-          StringIO.open(css) do |str|
+          StringIO.open(css.to_s) do |str|
             selector = ''
             while (char = str.getc)
               case char
diff --git a/lib/capybara/spec/session/has_css_spec.rb b/lib/capybara/spec/session/has_css_spec.rb
index c1989319..40730841 100644
--- a/lib/capybara/spec/session/has_css_spec.rb
+++ b/lib/capybara/spec/session/has_css_spec.rb
@@ -10,6 +10,13 @@ Capybara::SpecHelper.spec '#has_css?' do
     expect(@session).to have_css('p a#foo')
   end
 
+  it 'should take a symbol as the selector' do
+    # This was never a specifically accepted format but it has worked for a
+    # lot of versions. Probably should keep it until at least 4.0
+    # TODO: consider not supporting symbol for the CSS selector.
+    expect(@session).to have_css(:p)
+  end
+
   it 'should be false if the given selector is not on the page' do
     expect(@session).not_to have_css('abbr')
     expect(@session).not_to have_css('p a#doesnotexist')