diff --git a/lib/user_agent.rb b/lib/user_agent.rb
index f031a2b..6fdf9c9 100644
--- a/lib/user_agent.rb
+++ b/lib/user_agent.rb
@@ -14,9 +14,21 @@ class UserAgent
 
   DEFAULT_USER_AGENT = "Mozilla/4.0 (compatible)"
 
+  def self.default_user_agent
+    if instance_variable_defined?(:@default_user_agent)
+      @default_user_agent
+    else
+      DEFAULT_USER_AGENT
+    end
+  end
+
+  def self.default_user_agent=(value)
+    @default_user_agent = value
+  end
+
   def self.parse(string)
     if string.nil? || string.strip == ""
-      string = DEFAULT_USER_AGENT
+      string = default_user_agent
     end
 
     agents = Browsers::Base.new
diff --git a/spec/user_agent_spec.rb b/spec/user_agent_spec.rb
index f3d972d..d58181e 100644
--- a/spec/user_agent_spec.rb
+++ b/spec/user_agent_spec.rb
@@ -216,6 +216,11 @@
     expect(UserAgent.parse(" ")).to eq(default_user_agent)
   end
 
+  it "should allow changing the default agent" do
+    UserAgent.default_user_agent = "Mozilla/5.0 (Macintosh)"
+    expect(UserAgent.parse(nil)).to eq(UserAgent.parse("Mozilla/5.0 (Macintosh)"))
+  end
+
   it "should parse a double-quoted user-agent" do
     useragent = UserAgent.new("Mozilla", "5.0", ["X11", "Linux x86_64", "rv:9.0"])
     expect(UserAgent.parse("\"Mozilla/5.0 (X11; Linux x86_64; rv:9.0) Gecko/20100101 Firefox/8.0\"").application).to eq(useragent)