diff --git a/spec/form_spec.cr b/spec/form_spec.cr
index d111058..caaaad3 100644
--- a/spec/form_spec.cr
+++ b/spec/form_spec.cr
@@ -62,7 +62,7 @@ describe "Mechanize Form test" do
       checkbox.click
       checkbox.checked?.should eq true
     end
-    it "doesn't include request data if checkbox isn't checked" do
+    it "doesn't included in request data if checkbox isn't checked" do
       form.request_data.should contain("remember_me=on")
       checkbox.uncheck
       form.request_data.should_not contain("remember_me=")
@@ -96,5 +96,11 @@ describe "Mechanize Form test" do
       radiobuttons[1].checked.should eq true
       radiobuttons[0].checked.should eq false
     end
+    it "doesn't included in request data if checkbox isn't checked" do
+      radiobuttons[0].check
+      form.request_data.should contain "contact=email"
+      radiobuttons[0].uncheck
+      form.request_data.should_not contain "contact"
+    end
   end
 end
diff --git a/src/mechanize/form.cr b/src/mechanize/form.cr
index 9503972..bb71b3b 100644
--- a/src/mechanize/form.cr
+++ b/src/mechanize/form.cr
@@ -105,6 +105,27 @@ class MechanizeCr::Form
         successful_controls << elm
       end
     end
+    radio_groups = Hash(String, Array(FormContent::RadioButton)).new
+    radiobuttons.each do |radio|
+      name = radio.name
+      radio_groups[name] = Array(FormContent::RadioButton).new unless radio_groups.has_key?(name)
+      radio_groups[name] << radio
+    end
+
+    radio_groups.each_value do |g|
+      checked = g.select(&.checked)
+      if checked.uniq.size > 1
+        #values = checked.map(&.value).join(', ').inspect
+        #name = checked.first.name.inspect
+        #raise Mechanize::Error,
+        #      "radiobuttons #{values} are checked in the #{name} group, " \
+        #      "only one is allowed"
+        raise MechanizeCr::Error.new
+      else
+        successful_controls << checked.first unless checked.empty?
+      end
+    end
+
     successful_controls.each do |ctrl|
       value = ctrl.query_value
       next if value[0] == ""