diff --git a/lib/less/tree.js b/lib/less/tree.js
index 7038ecc4..134adbdf 100644
--- a/lib/less/tree.js
+++ b/lib/less/tree.js
@@ -23,7 +23,9 @@ tree.debugInfo.asComment = function(ctx) {
 };
 
 tree.debugInfo.asMediaQuery = function(ctx) {
-    return '@media -sass-debug-info{filename{font-family:"' + ctx.debugInfo.fileName + '";}line{font-family:"' + ctx.debugInfo.lineNumber + '";}}\n';
+    return '@media -sass-debug-info{filename{font-family:' +
+        ('file://' + ctx.debugInfo.fileName).replace(/[\/:.]/g, '\\$&') +
+        '}line{font-family:\\00003' + ctx.debugInfo.lineNumber + '}}\n';
 };
 
 tree.find = function (obj, fun) {