diff --git a/utils/convert.py b/utils/convert.py
index 4679298..7ddf363 100644
--- a/utils/convert.py
+++ b/utils/convert.py
@@ -70,7 +70,7 @@ def convert_to_data(value) -> float | int | str | None:
         return value
 
     value = value.strip()
-    if value in {"-", " "}:
+    if value in {"", "-", " "}:
         return None
 
     try: