diff --git a/tests/Makefile.include b/tests/Makefile.include
index 9f679c2f8e..7af278db55 100644
--- a/tests/Makefile.include
+++ b/tests/Makefile.include
@@ -834,7 +834,7 @@ $(patsubst %, check-qtest-%, $(QTEST_TARGETS)): check-qtest-%: $(check-qtest-y)
 	$(if $(CONFIG_GCOV),@rm -f *.gcda */*.gcda */*/*.gcda */*/*/*.gcda,)
 	$(call quiet-command,QTEST_QEMU_BINARY=$*-softmmu/qemu-system-$* \
 		QTEST_QEMU_IMG=qemu-img$(EXESUF) \
-		MALLOC_PERTURB_=$${MALLOC_PERTURB_:-$$((RANDOM % 255 + 1))} \
+		MALLOC_PERTURB_=$${MALLOC_PERTURB_:-$$(( $${RANDOM:-0} % 255 + 1))} \
 		gtester $(GTESTER_OPTIONS) -m=$(SPEED) $(check-qtest-$*-y) $(check-qtest-generic-y),"GTESTER","$@")
 	$(if $(CONFIG_GCOV),@for f in $(gcov-files-$*-y) $(gcov-files-generic-y); do \
 	  echo Gcov report for $$f:;\
@@ -845,7 +845,7 @@ $(patsubst %, check-qtest-%, $(QTEST_TARGETS)): check-qtest-%: $(check-qtest-y)
 $(patsubst %, check-%, $(check-unit-y) $(check-speed-y)): check-%: %
 	$(if $(CONFIG_GCOV),@rm -f *.gcda */*.gcda */*/*.gcda */*/*/*.gcda,)
 	$(call quiet-command, \
-		MALLOC_PERTURB_=$${MALLOC_PERTURB_:-$$((RANDOM % 255 + 1))} \
+		MALLOC_PERTURB_=$${MALLOC_PERTURB_:-$$(( $${RANDOM:-0} % 255 + 1))} \
 		gtester $(GTESTER_OPTIONS) -m=$(SPEED) $*,"GTESTER","$*")
 	$(if $(CONFIG_GCOV),@for f in $(gcov-files-$(subst tests/,,$*)-y) $(gcov-files-generic-y); do \
 	  echo Gcov report for $$f:;\