diff --git a/lib/coffee_script/nodes.rb b/lib/coffee_script/nodes.rb
index 55fdd6ef..00591410 100644
--- a/lib/coffee_script/nodes.rb
+++ b/lib/coffee_script/nodes.rb
@@ -724,7 +724,8 @@ module CoffeeScript
     end
 
     def compile(o={})
-      write("(#{@expression.compile(super(o))} != undefined)")
+      val = @expression.compile(super(o))
+      write("(typeof #{val} !== 'undefined' && #{val} !== null)")
     end
   end
 
diff --git a/test/fixtures/execution/test_existence.coffee b/test/fixtures/execution/test_existence.coffee
new file mode 100644
index 00000000..47bfbfab
--- /dev/null
+++ b/test/fixtures/execution/test_existence.coffee
@@ -0,0 +1,5 @@
+print(if my_special_variable? then false else true)
+
+my_special_variable: false
+
+print(if my_special_variable? then true else false)
\ No newline at end of file