diff --git a/Source/portable/IAR/ARM_CM3/portasm.s b/Source/portable/IAR/ARM_CM3/portasm.s
index 65522b5b2..14df393c2 100644
--- a/Source/portable/IAR/ARM_CM3/portasm.s
+++ b/Source/portable/IAR/ARM_CM3/portasm.s
@@ -148,6 +148,8 @@ vPortSVCHandler;
 	ldr r2, =uxCriticalNesting
 	str r1, [r2]
 	msr psp, r0
+	mov r0, #0
+	msr	basepri, r0
 	orr r14, r14, #13
 	bx r14