diff --git a/lib/subdomain-fu.rb b/lib/subdomain-fu.rb
index 40ead12..848b7db 100644
--- a/lib/subdomain-fu.rb
+++ b/lib/subdomain-fu.rb
@@ -136,7 +136,7 @@ def self.current_subdomain(request)
   def self.current_domain(request)
     domain = ""
     domain << request.subdomains[1..-1].join(".") + "." if request.subdomains.length > 1
-    domain << request.domain + request.port_string
+    domain << request.domain.to_s + request.port_string
   end
 
   module Controller
diff --git a/spec/subdomain_fu_spec.rb b/spec/subdomain_fu_spec.rb
index 5b1a246..3df42fe 100644
--- a/spec/subdomain_fu_spec.rb
+++ b/spec/subdomain_fu_spec.rb
@@ -175,6 +175,11 @@
       request = mock("request", :subdomains => [], :domain => "", :port_string => "")
       SubdomainFu.current_domain(request).should == ""
     end
+    
+    it "should return an IP address if there is only an IP address" do
+      request = mock("request", :subdomains => [], :domain => "127.0.0.1", :port_string => "")
+      SubdomainFu.current_domain(request).should == "127.0.0.1"
+    end
 
     it "should return the current domain if there is only one level of subdomains" do
       request = mock("request", :subdomains => ["www"], :domain => "example.com", :port_string => "")