diff --git a/subr/build_init.subr b/subr/build_init.subr
index fd91a6f..01ae9be 100644
--- a/subr/build_init.subr
+++ b/subr/build_init.subr
@@ -1,3 +1,12 @@
+build_ast() {
+	local _param="${1}" _pids_killed="";
+	rm -f "${DEFAULT_BUILD_STATUS_IN_PROGRESS_FNAME}";
+	case "${_param}" in
+	abort) ex_rtl_log_msg failexit "Build aborted."; ;;
+	esac;
+	ex_rtl_kill_tree "${$}"; ex_rtl_log_msg vnfo "Killed PIDs ${_pids_killed}";
+};
+
 build_fini() {
 	: $((BUILD_TIMES_SECS=$(ex_rtl_date %s)-${BUILD_TIMES_SECS}));
 	: $((BUILD_TIMES_HOURS=${BUILD_TIMES_SECS}/3600));
@@ -14,6 +23,9 @@ build_init() {
 	if ! awk -V 2>/dev/null | grep -q "^GNU Awk "; then
 		ex_rtl_log_msg failexit "Error: awk(1) in \$PATH must be GNU Awk.";
 	fi;
+	if ! which pgrep >/dev/null 2>&1; then
+		ex_rtl_log_msg failexit "Error: missing pgrep.";
+	fi;
 	if [ -z "${DEFAULT_BUILD_CPUS}" ]\
 	&& [ -e /proc/cpuinfo ]; then
 		DEFAULT_BUILD_CPUS=$(awk '/^processor/{cpus++} END{print cpus}' /proc/cpuinfo);
@@ -81,11 +93,7 @@ build_init() {
 	BUILD_NFINI="${BUILD_NSKIP:=${BUILD_NFAIL:=${BUILD_NBUILT:=0}}}";
 	BUILD_TIMES_SECS="$(ex_rtl_date %s)";
 	BUILD_PKGS_FAILED="";
-	trap "rm -f "${DEFAULT_BUILD_STATUS_IN_PROGRESS_FNAME}";	\
-		ex_rtl_log_msg failexit \"Build aborted.\";"		\
-		HUP INT TERM USR1 USR2;
-	trap "rm -f "${DEFAULT_BUILD_STATUS_IN_PROGRESS_FNAME}";"	\
-		EXIT;
+	trap "build_ast abort" HUP INT TERM USR1 USR2; trap "build_ast exit" EXIT;
 	for _vname in ${DEFAULT_CHECK_PATH_VARS}; do
 		_vname_val="$(ex_rtl_get_var_unsafe "${_vname}")";
 		if [ -z "${_vname_val}" ]; then
diff --git a/subr/ex_rtl.subr b/subr/ex_rtl.subr
index 3f5e8c7..6bbbe5e 100644
--- a/subr/ex_rtl.subr
+++ b/subr/ex_rtl.subr
@@ -17,6 +17,16 @@ ex_rtl_toupper() { echo "${1}" | tr a-z A-Z; };
 ex_rtl_uniq() { echo "${@}" | sed 's/ /\n/g' | awk '!x[$0]++' | paste -s -d" "; };
 ex_rtl_unset_vars() { while [ ${#} -gt 0 ]; do unset "${1}"; shift; done; };
 
+ex_rtl_kill_tree() {
+	local _pid="${1}" _signal="TERM" _pid_child="" _pid_top="";
+	for _pid_top in $(pgrep -P "${_pid}"); do
+		for _pid_child in $(pgrep -P "${_pid_top}" 2>/dev/null); do
+			_pids_killed="${_pids_killed:+${_pids_killed} }${_pid_child}"; kill "-${_signal}" "${_pid_child}" 2>/dev/null;
+		done;
+		_pids_killed="${_pids_killed:+${_pids_killed} }${_pid_child}"; kill "-${_signal}" "${_pid_child}" 2>/dev/null;
+	done;
+};
+
 ex_rtl_lfilter() {
 	local _list="${1}" _filter="${2}" _lnew="" _litem="" _litem_filter="" _filterfl="";
 	if [ -z "${_filter}" ]; then