diff --git a/lib/global_path.rb b/lib/global_path.rb
index 20f09f18bd4..c2d9a2a4da2 100644
--- a/lib/global_path.rb
+++ b/lib/global_path.rb
@@ -6,4 +6,13 @@ module GlobalPath
   def cdn_path(p)
     "#{GlobalSetting.cdn_url}#{path(p)}"
   end
+
+  def cdn_relative_path(path)
+    if (cdn_url = GlobalSetting.cdn_url).present?
+      URI.parse(cdn_url).path + path
+    else
+      path
+    end
+  end
+
 end
diff --git a/lib/tasks/assets.rake b/lib/tasks/assets.rake
index 040f70e2b29..ff109fbc289 100644
--- a/lib/tasks/assets.rake
+++ b/lib/tasks/assets.rake
@@ -102,8 +102,8 @@ end
 
 def compress_node(from,to)
   to_path = "#{assets_path}/#{to}"
-
-  source_map_root = (d=File.dirname(from)) == "." ? "/assets" : "/assets/#{d}"
+  assets = cdn_relative_path("/assets")
+  source_map_root = assets + (d=File.dirname(from)) == "." ? "" : "/#{d}"
   source_map_url = cdn_path "/assets/#{to}.map"
 
   cmd = "uglifyjs '#{assets_path}/#{from}' -p relative -c -m -o '#{to_path}' --source-map-root '#{source_map_root}' --source-map '#{assets_path}/#{to}.map' --source-map-url '#{source_map_url}'"
diff --git a/spec/components/global_path_spec.rb b/spec/components/global_path_spec.rb
new file mode 100644
index 00000000000..41b778c9af3
--- /dev/null
+++ b/spec/components/global_path_spec.rb
@@ -0,0 +1,30 @@
+require 'rails_helper'
+require 'global_path'
+
+class GlobalPathInstance
+  extend GlobalPath
+end
+
+describe GlobalPath do
+
+  context 'cdn_relative_path' do
+    def cdn_relative_path(p)
+      GlobalPathInstance.cdn_relative_path(p)
+    end
+
+    it "just returns path for no cdn" do
+      expect(cdn_relative_path("/test")).to eq("/test")
+    end
+
+    it "returns path when a cdn is defined with a path" do
+      GlobalSetting.expects(:cdn_url).returns("//something.com/foo")
+      expect(cdn_relative_path("/test")).to eq("/foo/test")
+    end
+
+    it "returns path when a cdn is defined with a path" do
+      GlobalSetting.expects(:cdn_url).returns("https://something.com:221/foo")
+      expect(cdn_relative_path("/test")).to eq("/foo/test")
+    end
+
+  end
+end