diff --git a/libexec/rc/rc.subr b/libexec/rc/rc.subr
--- a/libexec/rc/rc.subr
+++ b/libexec/rc/rc.subr
@@ -1132,7 +1132,7 @@
 	_keywords="start stop restart rcvar enable disable delete enabled describe extracommands $extra_commands"
 	rc_pid=
 	_pidcmd=
-	_procname=${procname:-${command}}
+	: "${procname:=${command}}"
 
 	eval _cpuset=\$${name}_cpuset
 
@@ -1164,11 +1164,11 @@
 	fi
 
 					# setup pid check command
-	if [ -n "$_procname" ]; then
+	if [ -n "$procname" ]; then
 		if [ -n "$pidfile" ]; then
-			_pidcmd='rc_pid=$(check_pidfile '"$pidfile $_procname $command_interpreter"')'
+			_pidcmd='rc_pid=$(check_pidfile '"$pidfile $procname $command_interpreter"')'
 		else
-			_pidcmd='rc_pid=$(check_process '"$_procname $command_interpreter"')'
+			_pidcmd='rc_pid=$(check_process '"$procname $command_interpreter"')'
 		fi
 		_keywords="${_keywords} status poll"
 	else
diff --git a/libexec/rc/tests/rc_subr_test.sh b/libexec/rc/tests/rc_subr_test.sh
--- a/libexec/rc/tests/rc_subr_test.sh
+++ b/libexec/rc/tests/rc_subr_test.sh
@@ -104,8 +104,72 @@
 		/bin/sh "$__script" "$__name" "$__pidfile" onestop
 }
 
+atf_test_case procname_run_rc_command_start
+procname_run_rc_command_start_head()
+{
+	atf_set "descr" "Verify that \${procname} is available when " \
+		"the service is onestarted via " \
+		"the default implementaion of the start argument " \
+		"in run_rc_command"
+}
+
+procname_run_rc_command_start_body()
+{
+	__name="$(atf_get ident)"
+	__command="/bin/echo"
+	__script=$(mktemp -t "${__name}.script")
+
+	cat >> "$__script" <<-'LITERAL'
+	. /etc/rc.subr
+	name="$1"
+	command="$2"
+	_rc_arg="$3"
+	command_args='$procname'
+	load_rc_config
+	rc_quiet="YES"
+	rc_startmsgs="NO"
+	run_rc_command "$_rc_arg"
+	LITERAL
+
+	atf_check -s exit:0 -o inline:"${__command}\n" -e empty \
+		/bin/sh "$__script" "$__name" "$__command" onestart
+}
+
+atf_test_case procname_start_cmd_func
+procname_start_cmd_func_head()
+{
+	atf_set "descr" "Verify that \${procname} is available when " \
+		"the service is onestarted via " \
+		"a function in start_cmd"
+}
+
+procname_start_cmd_func_body()
+{
+	__name="$(atf_get ident)"
+	__command="/bin/echo"
+	__script=$(mktemp -t "${__name}.script")
+
+	cat >> "$__script" <<-'LITERAL'
+	. /etc/rc.subr
+	name="$1"
+	command="$2"
+	_rc_arg="$3"
+	start_cmd="procname_start_cmd_func_start"
+	procname_start_cmd_func_start() {
+		"$command" "$procname"
+	}
+	load_rc_config
+	run_rc_command "$_rc_arg"
+	LITERAL
+
+	atf_check -s exit:0 -o inline:"${__command}\n" -e empty \
+		/bin/sh "$__script" "$__name" "$__command" onestart
+}
+
 atf_init_test_cases()
 {
 	atf_add_test_case oomprotect_all
 	atf_add_test_case oomprotect_yes
+	atf_add_test_case procname_run_rc_command_start
+	atf_add_test_case procname_start_cmd_func
 }