diff --git a/syntax/po.nanorc b/syntax/po.nanorc
index 4e66a2eb..a59dd229 100644
--- a/syntax/po.nanorc
+++ b/syntax/po.nanorc
@@ -22,8 +22,8 @@ color brightblue "^(msgid|msgid_plural|msgstr)\>"
 color red " fuzzy(,|$)"
 color yellow " (no-)?([a-z-]+|c\+\+)-format(,|$)"
 # Format specifiers.
-color brightmagenta "%([1-9]\$)?[#0 +'I-]?(\*([1-9]\$)?|[1-9](\.[0-9]?)?)?(hh|ll|[hlLjzt])?[diouxXeEfFgGaAcspnmr]|%<PRI[diouxX](32|64)>|%%"
-color rosy "%\([[:alpha:]][[:alnum:]_]*\)([1-9](\.[0-9])?)?[#0 +-]?[diouxXeEfFgGcrs]"
+color brightmagenta "%([1-9]\$)?[#0 +'I-]?(\*([1-9]\$)?|[0-9]\.?|[0-9]?\.[0-9])?(hh|ll|[hlLjzt])?([diouxXeEfFgGaAcspnmr]|<PRI[diouxX](32|64)>)|%%"
+color rosy "%\([[:alpha:]][[:alnum:]_]*\)([0-9]\.?|[0-9]?\.[0-9])?[#0 +-]?[diouxXeEfFgGcrs]"
 # Quotes and escaped characters.
 color yellow """
 color cyan "\\([abcefnrtv"\]|x[[:xdigit:]]{2}|[0-7]{3})"