diff --git a/source/dub/commandline.d b/source/dub/commandline.d
index 433ad7b..8143095 100644
--- a/source/dub/commandline.d
+++ b/source/dub/commandline.d
@@ -490,6 +490,8 @@
 			if (!package_name.length) return true;
 		}
 
+		enforce(package_name.length, "No valid root package found - aborting.");
+
 		auto pack = dub.packageManager.getFirstPackage(package_name);
 		enforce(pack, "Failed to find a package named '"~package_name~"'.");
 		logInfo("Building package %s in %s", pack.name, pack.path.toNativeString());