diff --git a/instanceinfo.sh b/instanceinfo.sh
index 2b9a47b..f625b2c 100755
--- a/instanceinfo.sh
+++ b/instanceinfo.sh
@@ -1,7 +1,7 @@
 #!/bin/bash
 # Print some basic info about fediverse instances.
 
-# Version: 2019-07-22_2
+# Version: 2019-07-23_1
 
 if [[ -z "${1}" ]]; then
     echo "usage: ${0} DOMAIN" >&2
@@ -98,7 +98,7 @@ function parse_mastodon()
         implementation="Florence"
     elif grep -Eq '"version":"[0-9]+\.[0-9]+\.[0-9]+"' <<<"${json}"; then
         implementation="Mastodon"
-    elif grep -Eq '"version":"[0-9]+\.[0-9]+\.[0-9][\._\-\+]?[a-zA-Z0-9]+"' <<<"${json}"; then
+    elif grep -Eq '"version":"[0-9]+\.[0-9]+\.[0-9][\._\-\+]?[a-zA-Z0-9\_\-\+]+"' <<<"${json}"; then
         implementation="Mastodon fork"
     fi
     if [[ -n "${implementation}" ]]; then