diff --git a/lib/source-map/util.js b/lib/source-map/util.js
index 0150216c..047b0544 100644
--- a/lib/source-map/util.js
+++ b/lib/source-map/util.js
@@ -198,15 +198,30 @@ define(function (require, exports, module) {
 
     aRoot = aRoot.replace(/\/$/, '');
 
-    // XXX: It is possible to remove this block, and the tests still pass!
-    var url = urlParse(aRoot);
-    if (aPath.charAt(0) == "/" && url && url.path == "/") {
-      return aPath.slice(1);
+    // It is possible for the path to be above the root. In this case, simply
+    // checking whether the root is a prefix of the path won't work. Instead, we
+    // need to remove components from the root one by one, until either we find
+    // a prefix that fits, or we run out of components to remove.
+    var level = 0;
+    while (aPath.indexOf(aRoot + '/') !== 0) {
+      var index = aRoot.lastIndexOf("/");
+      if (index < 0) {
+        return aPath;
+      }
+
+      // If the only part of the root that is left is the scheme (i.e. http://,
+      // file:///, etc.), one or more slashes (/), or simply nothing at all, we
+      // have exhausted all components, so the path is not relative to the root.
+      aRoot = aRoot.slice(0, index);
+      if (aRoot.match(/^([^\/]+:\/)?\/*$/)) {
+        return aPath;
+      }
+
+      ++level;
     }
 
-    return aPath.indexOf(aRoot + '/') === 0
-      ? aPath.substr(aRoot.length + 1)
-      : aPath;
+    // Make sure we add a "../" for each component we removed from the root.
+    return Array(level + 1).join("../") + aPath.substr(aRoot.length + 1);
   }
   exports.relative = relative;
 
diff --git a/test/source-map/test-source-map-consumer.js b/test/source-map/test-source-map-consumer.js
index 2b56713d..5b051de8 100644
--- a/test/source-map/test-source-map-consumer.js
+++ b/test/source-map/test-source-map-consumer.js
@@ -495,6 +495,29 @@ define(function (require, exports, module) {
     assert.equal(pos.column, 2);
   };
 
+  exports['test sourceRoot + generatedPositionFor for path above the root'] = function (assert, util) {
+    var map = new SourceMapGenerator({
+      sourceRoot: 'foo/bar',
+      file: 'baz.js'
+    });
+    map.addMapping({
+      original: { line: 1, column: 1 },
+      generated: { line: 2, column: 2 },
+      source: '../bang.coffee'
+    });
+    map = new SourceMapConsumer(map.toString());
+
+    // Should handle with sourceRoot.
+    var pos = map.generatedPositionFor({
+      line: 1,
+      column: 1,
+      source: 'foo/bang.coffee'
+    });
+
+    assert.equal(pos.line, 2);
+    assert.equal(pos.column, 2);
+  };
+
   exports['test allGeneratedPositionsFor for line'] = function (assert, util) {
     var map = new SourceMapGenerator({
       file: 'generated.js'
diff --git a/test/source-map/test-util.js b/test/source-map/test-util.js
index 997d1a26..530dbdbc 100644
--- a/test/source-map/test-util.js
+++ b/test/source-map/test-util.js
@@ -202,7 +202,11 @@ define(function (require, exports, module) {
   // TODO Issue #128: Define and test this function properly.
   exports['test relative()'] = function (assert, util) {
     assert.equal(libUtil.relative('/the/root', '/the/root/one.js'), 'one.js');
-    assert.equal(libUtil.relative('/the/root', '/the/rootone.js'), '/the/rootone.js');
+    assert.equal(libUtil.relative('http://the/root', 'http://the/root/one.js'), 'one.js');
+    assert.equal(libUtil.relative('/the/root', '/the/rootone.js'), '../rootone.js');
+    assert.equal(libUtil.relative('http://the/root', 'http://the/rootone.js'), '../rootone.js');
+    assert.equal(libUtil.relative('/the/root', '/therootone.js'), '/therootone.js');
+    assert.equal(libUtil.relative('http://the/root', '/therootone.js'), '/therootone.js');
 
     assert.equal(libUtil.relative('', '/the/root/one.js'), '/the/root/one.js');
     assert.equal(libUtil.relative('.', '/the/root/one.js'), '/the/root/one.js');