diff --git a/README.markdown b/README.markdown
index f16c951..4cead91 100644
--- a/README.markdown
+++ b/README.markdown
@@ -33,7 +33,12 @@ Here is the first example(with a little extra added) from the [haml][] site conv
     </div><div id="bio">Experienced software professional...
     </div></div></div></body></html>
 
-Note that this works almost the same as ruby's [haml][], but doesn't pretty print the html.  This would greatly slow down and complicate the code.  If you really want pretty printed html, then I suggest writing one using the xml parser library and process the resulting html..
+Note that this works almost the same as ruby's [haml][], but doesn't pretty print the html.  This would greatly slow down and complicate the code.  If you really want pretty printed html, then I suggest writing one using the xml parser library and process the resulting html.
+
+## Differences from Ruby HAML
+
+* `=` and `-` interpolate JavaScript code, not Ruby 
+* Multi-line attribute blocks are not supported.
 
 ## API
 
diff --git a/lib/haml.js b/lib/haml.js
index b726905..d7f4c5b 100755
--- a/lib/haml.js
+++ b/lib/haml.js
@@ -89,9 +89,10 @@ var Haml;
 
     for (i = 1; count > 0; i += 1) {
 
-      // If we reach the end of the line, then there is a problem
+      // If we reach the end of the line, then there is a problem, or the attribute block is multi-line.
+      // This behavior is unsupported in HAML-js
       if (i > l) {
-        throw "Malformed attribute block";
+        throw "Multi-line attribute blocks are unsupported in HAML-js";
       }
 
       c = line.charAt(i);