diff --git a/tuf/api/metadata.py b/tuf/api/metadata.py
index 58342dbf..00d5775e 100644
--- a/tuf/api/metadata.py
+++ b/tuf/api/metadata.py
@@ -622,7 +622,7 @@ def verify_signature(
             signature = metadata.signatures[self.keyid]
         except KeyError:
             raise exceptions.UnsignedMetadataError(
-                f"no signature for key {self.keyid} found in metadata"
+                f"No signature for key {self.keyid} found in metadata"
             ) from None
 
         if signed_serializer is None: