diff --git a/file_utils/prefixsubdirs.sh b/file_utils/prefixsubdirs.sh
index 9c296c4..3e0d29b 100755
--- a/file_utils/prefixsubdirs.sh
+++ b/file_utils/prefixsubdirs.sh
@@ -1,6 +1,6 @@
 #!/bin/sh
 #
-# prefixsubdirs.sh, Copyright © 2018 Matteo Cypriani
+# prefixsubdirs.sh, Copyright © 2018, 2021 Matteo Cypriani
 #
 # This program is free software. It comes without any warranty, to
 # the extent permitted by applicable law. You can redistribute it
@@ -45,6 +45,11 @@ while [ -n "$1" ] ; do
         continue
     fi
 
+    if [ "$dir" = '.' ] ; then
+        printf 'Warning! Using "." is not (yet) supported and the outcome is most likely not what you want: ignoring.\n' >&2
+        continue
+    fi
+
     printf 'Entering "%s" ...\n' "$dir"
     prefix_subdirs "$dir"
 done