diff --git a/normalisename.py b/normalisename.py
index 31df1b1..5743fe9 100644
--- a/normalisename.py
+++ b/normalisename.py
@@ -10,6 +10,8 @@ for file in argv[1:]:
                ''.join(ch for ch in file
                        if ch.isalnum()
                        or ch is ' '
-                       or ch is '.')
+                       or ch is '.'
+                       or ch is '-')    # dashes are ok
            )
-           .replace(' ', '_'))
\ No newline at end of file
+           .replace(' ', '_'))
+