diff --git a/lib/cyberarm_engine/ui/elements/check_box.rb b/lib/cyberarm_engine/ui/elements/check_box.rb
index ec1d8a9..25e315f 100644
--- a/lib/cyberarm_engine/ui/elements/check_box.rb
+++ b/lib/cyberarm_engine/ui/elements/check_box.rb
@@ -46,7 +46,7 @@ module CyberarmEngine
       end
 
       def value=(bool)
-        old_value = this.value
+        old_value = self.value
 
         @toggle_button.value = bool
         publish(:changed, bool) if bool != old_value
diff --git a/lib/cyberarm_engine/ui/elements/slider.rb b/lib/cyberarm_engine/ui/elements/slider.rb
index 8c087ed..bbc123a 100644
--- a/lib/cyberarm_engine/ui/elements/slider.rb
+++ b/lib/cyberarm_engine/ui/elements/slider.rb
@@ -94,7 +94,7 @@ module CyberarmEngine
       end
 
       def value=(n)
-        old_value = this.value
+        old_value = self.value
 
         @value = n
         position_handle