diff --git a/kernel/mips64/zsum.S b/kernel/mips64/zsum.S
index 129b97900..c8ae4e3ce 100644
--- a/kernel/mips64/zsum.S
+++ b/kernel/mips64/zsum.S
@@ -76,6 +76,7 @@
 	dsll	INCX, INCX, ZBASE_SHIFT
 
 	blez	N, .L999
+	blez    INCX, .L999
 	dsra	I, N, 2
 
 	blez	I, .L25