diff --git a/core/arch/arm/plat-stm32mp1/conf.mk b/core/arch/arm/plat-stm32mp1/conf.mk
index 94b104b9c90..17381082255 100644
--- a/core/arch/arm/plat-stm32mp1/conf.mk
+++ b/core/arch/arm/plat-stm32mp1/conf.mk
@@ -235,6 +235,7 @@ endif
 
 # Provision enough threads to pass xtest
 ifneq (,$(filter y,$(CFG_SCMI_PTA) $(CFG_STM32MP1_SCMI_SIP)))
+CFG_NUM_SYSTEM_THREADS ?= 1
 ifeq ($(CFG_WITH_PAGER),y)
 CFG_NUM_THREADS ?= 3
 else