diff --git a/lib/legacy/class.html b/lib/legacy/class.html
index 7a7436d8f3..b828ecb047 100644
--- a/lib/legacy/class.html
+++ b/lib/legacy/class.html
@@ -126,7 +126,7 @@
             }
           }
         } else {
-          Polymer._warn('behavior is null, check for missing or 404 import');
+          console.warn('behavior is null, check for missing or 404 import');
         }
       }
       return list;
diff --git a/lib/legacy/legacy-element-mixin.html b/lib/legacy/legacy-element-mixin.html
index 57cb51e273..6272b1cecf 100644
--- a/lib/legacy/legacy-element-mixin.html
+++ b/lib/legacy/legacy-element-mixin.html
@@ -15,7 +15,6 @@
 <link rel="import" href="../utils/import-href.html">
 <link rel="import" href="../utils/render-status.html">
 <link rel="import" href="../utils/unresolved.html">
-<link rel="import" href="mutable-data-behavior.html">
 <link rel="import" href="polymer.dom.html">
 
 <script>
diff --git a/polymer.html b/polymer.html
index 130a5c9ef7..0331373cd6 100644
--- a/polymer.html
+++ b/polymer.html
@@ -17,6 +17,8 @@
 <link rel="import" href="lib/elements/array-selector.html">
 <!-- custom-style -->
 <link rel="import" href="lib/elements/custom-style.html">
+<!-- bc behaviors -->
+<link rel="import" href="lib/legacy/mutable-data-behavior.html">
 <script>
   // bc
   Polymer.Base = Polymer.LegacyElementMixin(HTMLElement).prototype;
diff --git a/test/unit/property-effects-elements.html b/test/unit/property-effects-elements.html
index 4e4e1344ce..7005ec55b3 100644
--- a/test/unit/property-effects-elements.html
+++ b/test/unit/property-effects-elements.html
@@ -7,9 +7,6 @@
 Code distributed by Google as part of the polymer project is also
 subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
 -->
-<link rel="import" href="../../lib/legacy/mutable-data-behavior.html">
-<link rel="import" href="../../lib/mixins/mutable-data.html">
-
 <dom-module id="x-basic">
   <template>
     <div id="boundChild"