diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index 824a94fc413b..a93da805435f 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c
@@ -631,7 +631,7 @@ static inline u32 mpic_physmask(u32 cpumask)
 	int i;
 	u32 mask = 0;
 
-	for (i = 0; i < NR_CPUS; ++i, cpumask >>= 1)
+	for (i = 0; i < min(32, NR_CPUS); ++i, cpumask >>= 1)
 		mask |= (cpumask & 1) << get_hard_smp_processor_id(i);
 	return mask;
 }