diff --git a/tiramisu_api/api.py b/tiramisu_api/api.py
index b879146..a070074 100644
--- a/tiramisu_api/api.py
+++ b/tiramisu_api/api.py
@@ -1195,7 +1195,7 @@ class Config:
                     value: Any) -> bool:
         if not path in self.form or not 'pattern' in self.form[path]:
             return True
-        if value is None or value is '':
+        if value is None or value == '':
             match = True
         else:
             if isinstance(value, int):