diff --git a/lib/irb/completion.rb b/lib/irb/completion.rb
index 000658e..609dca3 100644
--- a/lib/irb/completion.rb
+++ b/lib/irb/completion.rb
@@ -157,7 +157,7 @@ module IRB
end
next if name != "IRB::Context" and
/^(IRB|SLex|RubyLex|RubyToken)/ =~ name
- candidates.concat m.instance_methods(false)
+ candidates.concat m.instance_methods(false).map { |m| m.to_s }
}
candidates.sort!
candidates.uniq!