diff --git a/Data/Slug.hs b/Data/Slug.hs
index b7726ab..a3fc74a 100644
--- a/Data/Slug.hs
+++ b/Data/Slug.hs
@@ -48,6 +48,7 @@ validChar c =
     ('A' <= c && c <= 'Z') ||
     ('a' <= c && c <= 'z') ||
     ('0' <= c && c <= '9') ||
+    c == '.' ||
     c == '-' ||
     c == '_'