diff --git a/lib/utils/templatize.js b/lib/utils/templatize.js
index a85852f174..c53abdab6f 100644
--- a/lib/utils/templatize.js
+++ b/lib/utils/templatize.js
@@ -578,14 +578,11 @@ function warnOnUndeclaredProperties(templateInfo, options, methodHost) {
     if (!declaredProps[prop] && !(instanceProps && instanceProps[prop])) {
       const effects = propertyEffects[prop];
       for (let i=0; i<effects.length; i++) {
-        const {parts} = effects[i].info.binding;
-        for (let j=0; j<parts.length; j++) {
-          const part = parts[j];
-          if (!part.literal && !(part.signature && part.signature.static)) {
-            console.warn(`Property '${prop}' used in template but not ` +
-              `declared in 'properties'; attribute will not be observed.`);
-            break;
-          }
+        const {part} = effects[i].info;
+        if (!part.literal && !(part.signature && part.signature.static)) {
+          console.warn(`Property '${prop}' used in template but not ` +
+            `declared in 'properties'; attribute will not be observed.`);
+          break;
         }
       }
     }