diff --git a/src/librustc_metadata/loader.rs b/src/librustc_metadata/loader.rs
index 81788e08c7ef..d1892b87f8bc 100644
--- a/src/librustc_metadata/loader.rs
+++ b/src/librustc_metadata/loader.rs
@@ -664,6 +664,8 @@ impl<'a> Context<'a> {
                 }
                 sess.err(&format!("extern location for {} is of an unknown type: {}",
                                  self.crate_name, loc.display()));
+                sess.help(&format!("file name should be lib*.rlib or {}*.{}",
+                                   dylibname.0, dylibname.1));
                 false
             });