diff --git a/UI/WebServerResources/GNUmakefile b/UI/WebServerResources/GNUmakefile
index 96127ae37..112e1fe6a 100644
--- a/UI/WebServerResources/GNUmakefile
+++ b/UI/WebServerResources/GNUmakefile
@@ -10,6 +10,7 @@ build-static-files:
 	else \
 	  bower install; \
 	fi
+	( cd bower_components/underscore/ && npm run-script build )
 	grunt build
 
 all :: build-static-files