diff --git a/kernel/mips64/sum.S b/kernel/mips64/sum.S
index 261630d49d..bc9541c480 100644
--- a/kernel/mips64/sum.S
+++ b/kernel/mips64/sum.S
@@ -76,6 +76,7 @@
 	dsll	INCX, INCX, BASE_SHIFT
 
 	blez	N, .L999
+	blez	INCX, .L999
 	li	TEMP, SIZE
 
 	bne	INCX, TEMP, .L20