diff --git a/libkeyringctl/types.py b/libkeyringctl/types.py
index 98222cd..a19c1a9 100644
--- a/libkeyringctl/types.py
+++ b/libkeyringctl/types.py
@@ -11,7 +11,7 @@ PacketKind = NewType("PacketKind", str)
 
 
 class Trust(Enum):
-    unknown = auto
+    unknown = auto()
     revoked = auto()
     marginal = auto()
     full = auto()