diff --git a/src/mechanize/form/check_box.cr b/src/mechanize/form/check_box.cr
index 7de65f3..fb5b897 100644
--- a/src/mechanize/form/check_box.cr
+++ b/src/mechanize/form/check_box.cr
@@ -1,7 +1,7 @@
 class MechanizeCr::FormContent::CheckBox < MechanizeCr::FormContent::Field
   property :checked
 
-  def initialize(node : Node | Myhtml::Node, value = "")
+  def initialize(node : Node | Myhtml::Node, value = nil)
     @checked = !!node["checked"]
     super(node, value)
   end
@@ -22,4 +22,8 @@ class MechanizeCr::FormContent::CheckBox < MechanizeCr::FormContent::Field
   def click
     checked ? uncheck : check
   end
+
+  def query_value
+    [@name, @value || "on"]
+  end
 end
diff --git a/src/mechanize/form/field.cr b/src/mechanize/form/field.cr
index be85cfe..bcff113 100644
--- a/src/mechanize/form/field.cr
+++ b/src/mechanize/form/field.cr
@@ -1,14 +1,14 @@
 class MechanizeCr::FormContent::Field
   getter :node
-  property value     : String
+  property value   : String?
   getter name      : String
   getter type      : String
-  getter raw_value : String
+  getter raw_value : String?
 
-  def initialize(node : Node | Myhtml::Node, value = "")
+  def initialize(node : Node | Myhtml::Node, value=nil)
     @node = node
     @name = node.fetch("name", "")
-    @value = value || node.fetch("value", "")
+    @value = value || node.fetch("value", nil)
     @type = node.fetch("type", "")
     @raw_value = value
   end