diff --git a/lib/xmet/rawins.py b/lib/xmet/rawins.py
index 5c36794..4e96ef3 100644
--- a/lib/xmet/rawins.py
+++ b/lib/xmet/rawins.py
@@ -23,7 +23,7 @@ class RawinsSample():
 
 class RawinsObs():
     def __init__(self, kind: str):
-        self.kind = str
+        self.kind: str         = kind
         self.values: list[str] = list()
 
     def read(self, value: str):