diff --git a/release/release.sh b/release/release.sh
--- a/release/release.sh
+++ b/release/release.sh
@@ -73,11 +73,11 @@
 
 	# The default git checkout server, and branches for src/, doc/,
 	# and ports/.
-	GITROOT="https://git.FreeBSD.org/"
-	SRCBRANCH="main"
-	PORTBRANCH="main"
-	GITSRC="src.git"
-	GITPORTS="ports.git"
+	: ${GITROOT="https://git.FreeBSD.org/"}
+	: ${SRCBRANCH="main"}
+	: ${PORTBRANCH="main"}
+	: ${GITSRC="src.git"}
+	: ${GITPORTS="ports.git"}
 
 	# Set for embedded device builds.
 	EMBEDDEDBUILD=
@@ -85,8 +85,8 @@
 	# The default make.conf and src.conf to use.  Set to /dev/null
 	# by default to avoid polluting the chroot(8) environment with
 	# non-default settings.
-	MAKE_CONF="/dev/null"
-	SRC_CONF="/dev/null"
+	: ${MAKE_CONF="/dev/null"}
+	: ${SRC_CONF="/dev/null"}
 
 	# The number of make(1) jobs, defaults to the number of CPUs available
 	# for buildworld, and half of number of CPUs available for buildkernel