diff --git a/build/build.js b/build/build.js
index 2f82af391..563861373 100644
--- a/build/build.js
+++ b/build/build.js
@@ -32,7 +32,12 @@ async function build(opts) {
       ]),
       onwarn: function (message) {
         if (message.code === 'UNRESOLVED_IMPORT') {
-          throw new Error(`Could not resolve module ` + message.source + `. Try running 'npm install'`)
+          throw new Error(
+            `Could not resolve module ` + 
+            message.source + 
+            `. Try running 'npm install' or using rollup's 'external' option if this is an external dependency. ` +
+            `Module ${message.source} is imported in ${message.importer}`
+            )
         }
       }
     })