diff --git a/README.pod b/README.pod
index 1ce2f96..cbef50e 100644
--- a/README.pod
+++ b/README.pod
@@ -13,13 +13,15 @@ L<https://freedns.afraid.org>; the software goals are for simplicity,
 flexibility and configurability while using the minimal system tools
 installed with most distributions.
 
- Version 1.x = FreeDNS API v1
- Version 2.x = FreeDNS API v2
-
 If upgrading from API v1 to v2, a manual action is required on the
 FreeDNS website to generate a new API key for each domain name. See
 L<https://freedns.afraid.org/dynamic/v2/> for more information.
 
+By default, petrified will use the length of the API key to automatically
+choose the APIv1 or APIv2 URL; this can be overridden in the configuration
+file to force a specific version, as the v1 key length is variable but the
+v2 key length is fixed at 24 chars.
+
 =head1 OPTIONS
 
 =over 4
diff --git a/petrified b/petrified
index f5ff1ee..77fccf2 100755
--- a/petrified
+++ b/petrified
@@ -38,9 +38,18 @@ while getopts ":c:" opt; do
 done
 
 ## v2 API - How to update DNS - DDNS_KEY is unique per domain
-DDNS_URL=https://sync.afraid.org/u/
+DDNS_URL=""
 DDNS_KEY=""
 
+## From Josh, v1 key is variable but v2 is fixed length @24char. When set
+## to 0 (auto) the length of the DDNS_KEY will be used to choose which API
+## endpoint, otherwise specify 1 (API v1) or 2 (API v2) directly
+DDNS_API=0
+
+## API URL endpoints, no trailing slashes
+DDNS_V1U=https://freedns.afraid.org/dynamic/update.php
+DDNS_V2U=https://sync.afraid.org/u
+
 ## Which URL to use to get an IP
 # IPv4 icanhazip (http://major.io/icanhazip-com-faq/)
 DDNS_CHECK="http://4.icanhazip.com"
@@ -106,6 +115,28 @@ fi
 if [[ -z "${DDNS_KEY}" ]]; then
   echo "DDNS_KEY must be configured, exiting."
   exit 1
+else
+  # Set the API version endpoint, IP added later
+  case ${DDNS_API} in
+    0)
+      # From Josh, v2 is fixed @24 but v1 is variable (typically >24)
+      if [[ ${#DDNS_KEY} -ne 24 ]]; then
+        DDNS_URL="${DDNS_V1U}?${DDNS_KEY}&address="
+      else
+        DDNS_URL="${DDNS_V2U}/${DDNS_KEY}/?ip="
+      fi
+      ;;
+    1)
+      DDNS_URL="${DDNS_V1U}?${DDNS_KEY}&address="
+      ;;
+    2)
+      DDNS_URL="${DDNS_V2U}/${DDNS_KEY}/?ip="
+      ;;
+    *)
+      echo "DDNS_API must be 0, 1 or 2; exiting."
+      exit 1
+      ;;
+  esac
 fi
 
 # Make sure that PET_LOG will work if required
@@ -219,7 +250,7 @@ fi
 # If they don't match, tell upstream
 __UPDATED=0
 if [[ "${OLDIP}" != "${NEWIP}" ]]; then
-  UPDURL="${DDNS_URL}${DDNS_KEY}/?ip=${NEWIP}"
+  UPDURL="${DDNS_URL}${NEWIP}"
   RESULT=$(curl -m ${CURL_WAIT} -sk "${UPDURL}" 2>/dev/null)
   logmsg "${RESULT}"
   # "Updated foo from 1.2.3.4 to 5.6.7.8"
diff --git a/petrified.1 b/petrified.1
index 9285d2c..2aaff62 100644
--- a/petrified.1
+++ b/petrified.1
@@ -129,7 +129,7 @@
 .\" ========================================================================
 .\"
 .IX Title "PETRIFIED 1"
-.TH PETRIFIED 1 "2017-09-16" "petrified 2.0.0" "Petrified Manual"
+.TH PETRIFIED 1 "2017-09-29" "petrified 2.0.0" "Petrified Manual"
 .\" For nroff, turn off justification.  Always turn off hyphenation; it makes
 .\" way too many mistakes in technical documents.
 .if n .ad l
@@ -146,14 +146,14 @@ Usage: \fBpetrified\fR [ \fB\-c\fR \fIconfig\fR ]
 flexibility and configurability while using the minimal system tools
 installed with most distributions.
 .PP
-.Vb 2
-\& Version 1.x = FreeDNS API v1
-\& Version 2.x = FreeDNS API v2
-.Ve
-.PP
 If upgrading from \s-1API\s0 v1 to v2, a manual action is required on the
 FreeDNS website to generate a new \s-1API\s0 key for each domain name. See
 <https://freedns.afraid.org/dynamic/v2/> for more information.
+.PP
+By default, petrified will use the length of the \s-1API\s0 key to automatically
+choose the APIv1 or APIv2 \s-1URL\s0; this can be overridden in the configuration
+file to force a specific version, as the v1 key length is variable but the
+v2 key length is fixed at 24 chars.
 .SH "OPTIONS"
 .IX Header "OPTIONS"
 .IP "\fB\-c\fR \fIconfig\fR" 4
diff --git a/petrified.conf b/petrified.conf
index a5ac4ad..ad689c2 100644
--- a/petrified.conf
+++ b/petrified.conf
@@ -13,14 +13,26 @@
 # See petrified.crontab for examples on how to run via cron/fcron.
 
 
-# This is the unique string for the dynamic DNS entry to update; visit
-# https://freedns.afraid.org/dynamic/v2/ - next to the DNS entries towards
-# the bottom is a link to sync.afraid.org; copy that and extract the string
-# after the '.../u/' part and put here.
+# This is the unique key for the dynamic DNS entry to update; visit:
+#   https://freedns.afraid.org/dynamic/    (v1 API) or
+#   https://freedns.afraid.org/dynamic/v2/ (v2 API)
+# Next to the DNS entries towards the bottom is a link to afraid.org;
+# copy that and extract the string and put here, this is your API key.
 #
-# Example: DDNS_KEY=ZIfSWnXKuDqMpNEsTXBA852
+# Example v1: DDNS_KEY=9C4yjq3kaekkYNbYsKRqcosTmouMYbfVMLkJtR==
+# Example v2: DDNS_KEY=ZIfSWnXKuDqMpNEsTXBA852
 DDNS_KEY=
 
+# The migration from API v1 to API v2 requires the user to visit the
+# website and click a few buttons to generate a new API key for each
+# domain; the API v1 length is variable but API v2 is a fixed length
+# at 24 chars. This setting will try and autodetect the API version by
+# the length of DDNS_KEY - if 24, use v2 else use v1.
+# 0 = auto
+# 1 = force API v1
+# 2 = force API v2
+DDNS_API=0
+
 # Which URL to use to get an IP - the expectation is output from this
 # host in plain text, just the IP - no parsing will be done. The
 # icanhazip service returns the IPv4 and IPv6 nice and clean.