diff --git a/Makefile b/Makefile
index 5f7473c65..0590fb634 100644
--- a/Makefile
+++ b/Makefile
@@ -44,19 +44,15 @@ _CORE_NEXT=	${CORE_ABI:C/\./ /}
 .if ${_CORE_NEXT:[2]} == 7 # community
 CORE_NEXT!=	expr ${_CORE_NEXT:[1]} + 1
 CORE_NEXT:=	${CORE_NEXT}.1
-CORE_ALTABI?=	${CORE_ABI}
 .elif ${_CORE_NEXT:[2]} == 10 # business
 CORE_NEXT!=	expr ${_CORE_NEXT:[1]} + 1
 CORE_NEXT:=	${CORE_NEXT}.4
-CORE_ALTABI?=	${_CORE_NEXT:[1]}.7
 .elif ${_CORE_NEXT:[2]} == 1 # community
 CORE_NEXT=	${_CORE_NEXT:[1]}
 CORE_NEXT:=	${CORE_NEXT}.7
-CORE_ALTABI?=	${CORE_ABI}
 .elif ${_CORE_NEXT:[2]} == 4 # business
 CORE_NEXT=	${_CORE_NEXT:[1]}
 CORE_NEXT:=	${CORE_NEXT}.10
-CORE_ALTABI?=	${_CORE_NEXT:[1]}.1
 .else
 .error Unsupported minor version for CORE_ABI=${CORE_ABI}
 .endif
diff --git a/Mk/defaults.mk b/Mk/defaults.mk
index 480808e1e..9c4e1190e 100644
--- a/Mk/defaults.mk
+++ b/Mk/defaults.mk
@@ -76,7 +76,6 @@ CORE_SYSLOGNG?=  ${_CORE_SYSLOGNG:S/./ /g:[1..2]:tW:S/ /./g}
 .endif
 
 REPLACEMENTS=	CORE_ABI \
-		CORE_ALTABI \
 		CORE_ARCH \
 		CORE_COMMIT \
 		CORE_COPYRIGHT_HOLDER \
diff --git a/src/man/man8/opnsense-version.8 b/src/man/man8/opnsense-version.8
index 5add9c196..1eb2f99ab 100644
--- a/src/man/man8/opnsense-version.8
+++ b/src/man/man8/opnsense-version.8
@@ -24,7 +24,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd August 17, 2021
+.Dd November 9, 2021
 .Dt OPNSENSE-VERSION 8
 .Os
 .Sh NAME
@@ -93,8 +93,12 @@ Return the package series.
 Return the package version.
 .It Fl w
 Return the product version website.
-.It Fl a
-Return the firmware ALTABI string.
+.It Fl x
+Return the required ABI string.
+This is necessary for detecting an ABI-crossing that
+requires a clean reinstall of all packages and for
+manipulating the target ABI going to and away from
+the business mirror.
 .El
 .Sh FILES
 .Bl -tag -width Ds
diff --git a/src/opnsense/version/core.in b/src/opnsense/version/core.in
index 2ce7bf159..e7aa1b5c9 100644
--- a/src/opnsense/version/core.in
+++ b/src/opnsense/version/core.in
@@ -1,6 +1,5 @@
 {
     "product_abi": "%%CORE_ABI%%",
-    "product_altabi": "%%CORE_ALTABI%%",
     "product_arch": "%%CORE_ARCH%%",
     "product_copyright_owner": "%%CORE_COPYRIGHT_HOLDER%%",
     "product_copyright_url": "%%CORE_COPYRIGHT_WWW%%",
diff --git a/src/sbin/opnsense-version b/src/sbin/opnsense-version
index 9d4b29486..7fb38cd95 100755
--- a/src/sbin/opnsense-version
+++ b/src/sbin/opnsense-version
@@ -25,6 +25,7 @@
 
 DEFAULTS="\${product_name} \${product_version}"
 VERSIONDIR="/usr/local/opnsense/version"
+PLUGINCTL="/usr/local/sbin/pluginctl"
 OPENSSL="/usr/local/bin/openssl"
 PKG="/usr/local/sbin/pkg-static"
 TARGET="core"
@@ -74,7 +75,7 @@ while getopts AacefHiNnsVvwx OPT; do
 		OUTPUT="${OUTPUT} \${product_website}"
 		;;
 	x)
-		OUTPUT="${OUTPUT} \${product_altabi}"
+		OUTPUT="${OUTPUT} \${target_abi_major}.\${target_abi_minor}"
 		;;
 	*)
 		echo "Usage: man ${0##*/}" >&2
@@ -128,6 +129,36 @@ core)
 		RESULT=$(${PKG} info -s ${product_id})
 		product_size=${RESULT##* }
 	fi
+	if [ -z "${OUTPUT%%*target_abi*}" -a -f ${PLUGINCTL} ]; then
+		target_abi_major=${product_abi%%.*}
+		target_abi_minor=${product_abi#*.}
+
+		IS_BUSINESS=$(echo ${product_name} | grep -c -- '-business')
+		WANT_BUSINESS=$(${PLUGINCTL} -g system.firmware.mirror | \
+		    grep -c 'opnsense-update\.deciso\.com')
+
+		if [ "${IS_BUSINESS}${WANT_BUSINESS}" = "01" -o ]; then
+			case ${target_abi_minor} in
+			1[0-2])
+				target_abi_major=$((target_abi_major + 1))
+				target_abi_minor=$((target_abi_minor - 9))
+				;;
+			*)
+				target_abi_minor=$((target_abi_minor + 3))
+				;;
+			esac
+		elif [ "${IS_BUSINESS}${WANT_BUSINESS}" = "10" ]; then
+			case ${target_abi_minor} in
+			[1-3])
+				target_abi_major=$((target_abi_major - 1))
+				target_abi_minor=$((target_abi_minor + 9))
+				;;
+			*)
+				target_abi_minor=$((target_abi_minor - 3))
+				;;
+			esac
+		fi
+	fi
 	;;
 *)
 	if [ -z "${OUTPUT}" ]; then