diff --git a/todo.sh b/todo.sh
index 1de99af..c7d8564 100755
--- a/todo.sh
+++ b/todo.sh
@@ -1009,7 +1009,7 @@ _format()
                         printf "%s", ctx_beg words[i] ctx_end
                     } else if (words[i] ~ /^(19|20)[0-9][0-9]-(0[1-9]|1[012])-(0[1-9]|[12][0-9]|3[01])$/) {
                         printf "%s", dat_beg words[i] dat_end
-                    } else if (words[i] ~ /^[[:alnum:]]+:[^ ]+$/) {
+                    } else if (words[i] ~ /^[A-Za-z0-9]+:[^ ]+$/) {
                         printf "%s", met_beg words[i] met_end
                     } else {
                         printf "%s", words[i]