diff --git a/emmet-core/emmet/core/vasp/material.py b/emmet-core/emmet/core/vasp/material.py
index 7613abd3c4..8d2dfbeb8f 100644
--- a/emmet-core/emmet/core/vasp/material.py
+++ b/emmet-core/emmet/core/vasp/material.py
@@ -54,7 +54,7 @@ def from_tasks(
             quality_scores: quality scores for various calculation types
             use_statics: Use statics to define a material
         """
-        if task_group == 0:
+        if len(task_group) == 0:
             raise Exception("Must have more than one task in the group.")
 
         # Material ID