diff --git a/_data/signed/Artuchka b/_data/signed/Artuchka.yaml
similarity index 100%
rename from _data/signed/Artuchka
rename to _data/signed/Artuchka.yaml
diff --git a/_data/signed/Roman2dot0 .yaml b/_data/signed/Roman2dot0.yaml
similarity index 100%
rename from _data/signed/Roman2dot0 .yaml
rename to _data/signed/Roman2dot0.yaml
diff --git a/_data/signed/alula.yml b/_data/signed/alula.yaml
similarity index 100%
rename from _data/signed/alula.yml
rename to _data/signed/alula.yaml
diff --git a/_data/signed/emad-elsaid.yml b/_data/signed/emad-elsaid.yaml
similarity index 100%
rename from _data/signed/emad-elsaid.yml
rename to _data/signed/emad-elsaid.yaml
diff --git a/_data/signed/iamserje.yaml b/_data/signed/iamserje.yaml
index b3a023dc..c2394411 100644
--- a/_data/signed/iamserje.yaml
+++ b/_data/signed/iamserje.yaml
@@ -1,2 +1,2 @@
 name: Serguei Voronkov
-link: iamserje@yandex.ru
+link: mailto:iamserje@yandex.ru
diff --git a/_data/signed/lutrin.yml b/_data/signed/lutrin.yaml
similarity index 100%
rename from _data/signed/lutrin.yml
rename to _data/signed/lutrin.yaml
diff --git a/check-signatures-format.py b/check-signatures-format.py
index 046b79ff..467a4749 100644
--- a/check-signatures-format.py
+++ b/check-signatures-format.py
@@ -6,6 +6,9 @@ regex = re.compile(r"name: (\S+\s)*\S+\nlink: (/#|(https?://|mailto:)[a-zA-Z0-9_
 
 ok = True
 for file_name in sorted(os.listdir("_data/signed")):
+    if not file_name.endswith(".yaml") or file_name[:-5] != file_name[:-5].strip():
+        print(file_name, "has invalid name")
+        ok = False
     with open(f"_data/signed/{file_name}") as f:
         contents = f.read()
     if not re.fullmatch(regex, contents):