diff --git a/tests/mutex_order/Makefile b/tests/mutex_order/Makefile
index 1d4146a98..146582816 100644
--- a/tests/mutex_order/Makefile
+++ b/tests/mutex_order/Makefile
@@ -5,3 +5,8 @@ BOARD_INSUFFICIENT_MEMORY := stm32f0discovery weio nucleo-f030 nucleo32-f042 nuc
                              nucleo-l053
 
 include $(RIOTBASE)/Makefile.include
+
+test:
+# `testrunner` calls `make term` recursively, results in duplicated `TERMFLAGS`.
+# So clears `TERMFLAGS` before run.
+	TERMFLAGS= tests/01-run.py