diff --git a/lib/csswring.js b/lib/csswring.js
index 76c8fb9..78acde1 100644
--- a/lib/csswring.js
+++ b/lib/csswring.js
@@ -48,6 +48,11 @@ var unquoteFontFamily = function (family) {
 var toRGBColor = function (m, leading, color) {
   color = onecolor(color);
 
+  // one.color failed to parse `color`
+  if (!color) {
+    return m;
+  }
+
   if (color.alpha() < 1) {
     return leading + color.cssa();
   }