diff --git a/tests/functions.sh b/tests/functions.sh
index 3d7bb89bc..67fab1d83 100644
--- a/tests/functions.sh
+++ b/tests/functions.sh
@@ -425,7 +425,9 @@ function ts_run {
 	while true; do
 		case "$1" in
 			--unbuffered)
-				UNBUFFERED=1
+				if type stdbuf >/dev/null 2>&1; then
+					UNBUFFERED=1
+				fi
 				shift;;
 			--)
 				shift
@@ -435,33 +437,34 @@ function ts_run {
 		esac
 	done
 
-	declare -a args
-
 	#
 	# ASAN mode
 	#
 	if [ "$TS_ENABLE_ASAN" == "yes" ]; then
-		args+=(ASAN_OPTIONS='detect_leaks=1')
-	fi
-
-	#
-	# Disable buffering of stdout
-	#
-	if [ -n "$UNBUFFERED" ]; then
-		if type stdbuf >/dev/null 2>&1; then
-			args+=(stdbuf --output=0)
+		if [ -n "$UNBUFFERED" ]; then
+			ASAN_OPTIONS='detect_leaks=1' unbuffer "$@"
+		else
+			ASAN_OPTIONS='detect_leaks=1' "$@"
 		fi
-	fi
 
 	#
 	# valgrind mode
 	#
-	if [ -n "$TS_VALGRIND_CMD" ]; then
-		args+=(libtool --mode=execute "$TS_VALGRIND_CMD" --tool=memcheck --leak-check=full)
-		args+=(--leak-resolution=high --num-callers=20 --log-file="$TS_VGDUMP")
+	elif [ -n "$TS_VALGRIND_CMD" ]; then
+                libtool --mode=execute \
+                $TS_VALGRIND_CMD --tool=memcheck --leak-check=full \
+                                 --leak-resolution=high --num-callers=20 \
+                                 --log-file="$TS_VGDUMP" "$@"
+	#
+	# default mode
+	#
+	else
+		if [ -n "$UNBUFFERED" ]; then
+			unbuffer "$@"
+		else
+			"$@"
+		fi
 	fi
-
-	"${args[@]}" "$@"
 }
 
 function ts_gen_diff {
diff --git a/tests/ts/libfdisk/mkpart-full b/tests/ts/libfdisk/mkpart-full
index 9fb46ef67..4724074ef 100755
--- a/tests/ts/libfdisk/mkpart-full
+++ b/tests/ts/libfdisk/mkpart-full
@@ -27,6 +27,7 @@ TESTPROG="$TS_HELPER_LIBFDISK_MKPART_FULLSPEC"
 ts_check_test_command "$TESTPROG"
 ts_check_test_command "$TS_CMD_SFDISK"
 ts_check_test_command "$TS_CMD_WIPEFS"
+ts_check_prog unbuffer
 
 TEST_IMAGE_NAME=$(ts_image_init 15)
 
diff --git a/tests/ts/misc/swaplabel b/tests/ts/misc/swaplabel
index 106cb7d21..438846426 100755
--- a/tests/ts/misc/swaplabel
+++ b/tests/ts/misc/swaplabel
@@ -21,6 +21,7 @@ ts_init "$*"
 ts_check_test_command "$TS_CMD_MKSWAP"
 ts_check_test_command "$TS_CMD_SWAPLABEL"
 ts_check_test_command "$TS_HELPER_SYSINFO"
+ts_check_prog unbuffer
 
 # fallocate does not work on most file systems
 function fallocate_or_skip()
diff --git a/tests/ts/rename/exit_codes b/tests/ts/rename/exit_codes
index d3012ae59..5ebd37a29 100755
--- a/tests/ts/rename/exit_codes
+++ b/tests/ts/rename/exit_codes
@@ -22,6 +22,8 @@ TS_DESC="exit codes"
 ts_init "$*"
 
 ts_check_test_command "$TS_CMD_RENAME"
+ts_check_prog unbuffer
+
 ts_cd "$TS_OUTDIR"
 
 touch rename_exit_codes.{1..2}