diff --git a/lib/shrink.js b/lib/shrink.js
index f95c7b9..8d62901 100644
--- a/lib/shrink.js
+++ b/lib/shrink.js
@@ -62,6 +62,11 @@ function traverseAST(ast) {
 }
 
 exports.shrink = function shrink(css) {
+  // Don't process if there isn't any CSS to process
+  if (css.replace(/[ \t]/g, '').length === 0) {
+    return '';
+  }
+
   var ast = gonzo.parse(css);
   ast = traverseAST(ast);
   return gonzo.toCSS(ast);