diff --git a/lib/compass/sass_extensions.rb b/lib/compass/sass_extensions.rb
index 0b89610d..8649ee06 100644
--- a/lib/compass/sass_extensions.rb
+++ b/lib/compass/sass_extensions.rb
@@ -1,3 +1,7 @@
+unless Sass::Script::Functions.methods.grep(/\Adeclare\Z/).any?
+  raise LoadError, "It looks like you've got an incompatible version of Sass. This often happens when you have an old haml gem installed. Please upgrade Haml to v3.1 or above."
+end
+
 module Compass::SassExtensions
 end