diff --git a/src/lib/style-properties.html b/src/lib/style-properties.html
index cab2d78bbd..33d9f52e74 100644
--- a/src/lib/style-properties.html
+++ b/src/lib/style-properties.html
@@ -152,7 +152,7 @@
               pp[1] = pp[1].trim();
               pp[1] = this.valueForProperty(pp[1], props) || pp[1];
             }
-            p = pp.join(': ');
+            p = pp.join(':');
           }
           parts[i] = (p && p.lastIndexOf(';') === p.length - 1) ? 
             // strip trailing ;
diff --git a/test/unit/styling-cross-scope-apply.html b/test/unit/styling-cross-scope-apply.html
index 41864677b1..cfd2ad181c 100644
--- a/test/unit/styling-cross-scope-apply.html
+++ b/test/unit/styling-cross-scope-apply.html
@@ -26,6 +26,7 @@
 
         --mixin2: {
           border: 3px solid seagreen;
+          background: url(http://www.google.com/icon.png);
         };
       }
       
@@ -177,6 +178,13 @@
     assertComputed(styled.$.mixin4, '2px', 'margin-top');
   });
 
+  test('mixins apply with url values', function() {
+    var url = 'http://www.google.com/icon.png';
+    var e = styled.$.child;
+    assert.include(e._styleProperties['--mixin2'], url);
+    assert.include(e._customStyle.textContent, url);
+  });
+
   test('variable mixins inherit and override', function() {
     var e = styled.$.child;
     assertComputed(e.$.mixin1, '1px');