diff --git a/lib/lockfile.ts b/lib/lockfile.ts
index 76b1f3fd..a3141a28 100644
--- a/lib/lockfile.ts
+++ b/lib/lockfile.ts
@@ -25,7 +25,7 @@ const isLockFileJson = is.ObjectOf({
   })),
   remote: is.OptionalOf(is.RecordOf(is.String, is.String)),
   workspace: is.OptionalOf(is.ObjectOf({
-    dependencies: is.ArrayOf(is.String),
+    dependencies: is.OptionalOf(is.ArrayOf(is.String)),
   })),
 });