diff --git a/lib/sass/tree/attr_node.rb b/lib/sass/tree/attr_node.rb
index 90127047..f89cb14f 100644
--- a/lib/sass/tree/attr_node.rb
+++ b/lib/sass/tree/attr_node.rb
@@ -40,5 +40,11 @@ module Sass::Tree
     def declaration
       ":#{name} #{value}"
     end
+
+    def invalid_child?(child)
+      if !child.is_a?(AttrNode)
+        "Illegal nesting: Only attributes may be nested beneath attributes."
+      end
+    end
   end
 end
diff --git a/lib/sass/tree/node.rb b/lib/sass/tree/node.rb
index 4655a50f..82739efb 100644
--- a/lib/sass/tree/node.rb
+++ b/lib/sass/tree/node.rb
@@ -10,6 +10,9 @@ module Sass
       end
 
       def <<(child)
+        if msg = invalid_child?(child)
+          raise Sass::SyntaxError.new(msg, child.line)
+        end
         @children << child
       end
       
@@ -24,6 +27,15 @@ module Sass
         end
         result[0...-1]
       end
+
+      private
+
+      # This method should be overridden by subclasses to return an error message
+      # if the given child node is invalid,
+      # and false or nil otherwise.
+      def invalid_child?(child)
+        false
+      end
     end
   end
 end
diff --git a/test/sass/engine_test.rb b/test/sass/engine_test.rb
index 454d04bd..cdf15b64 100644
--- a/test/sass/engine_test.rb
+++ b/test/sass/engine_test.rb
@@ -33,7 +33,8 @@ class SassEngineTest < Test::Unit::TestCase
     "a\n    :b c" => "Illegal Indentation: Only two space characters are allowed as tabulation.",
     "a\n  :b c\n  !d = 3" => "Constants may only be declared at the root of a document.",
     "!a = 1b + 2c" => "Incompatible units: b and c",
-    "& a\n  :b c" => "Base-level rules cannot contain the parent-selector-referencing character '&'"
+    "& a\n  :b c" => "Base-level rules cannot contain the parent-selector-referencing character '&'",
+    "a\n  :b\n    c" => "Illegal nesting: Only attributes may be nested beneath attributes."
   }
   
   def test_basic_render