diff --git a/lib/haml/compiler.rb b/lib/haml/compiler.rb
index d8962823..ebcff77f 100755
--- a/lib/haml/compiler.rb
+++ b/lib/haml/compiler.rb
@@ -14,7 +14,7 @@ extend Haml::Helpers
 _hamlout = @haml_buffer = Haml::Buffer.new(haml_buffer, #{options_for_buffer.inspect})
 _erbout = _hamlout.buffer
 END
-      preamble << "__in_erb_template = true;" unless ap_geq_3?
+      preamble << "__in_erb_template = true;" if rails_env && !ap_geq_3?
       postamble = <<END.gsub("\n", ";")
 #{precompiled_method_return_value}
 ensure