diff --git a/sys/conf/kern.pre.mk b/sys/conf/kern.pre.mk
index e23db1f3f0e..17e96d59101 100644
--- a/sys/conf/kern.pre.mk
+++ b/sys/conf/kern.pre.mk
@@ -19,7 +19,7 @@ SIZE?=		size
 .if ${CC} == "icc"
 COPTFLAGS?=-O
 .else
-. if ${MACHINE_ARCH} == "amd64"
+. if ${MACHINE_ARCH} == "amd64" || ${MACHINE_ARCH} == "sparc64"
 COPTFLAGS?=-O2 -frename-registers -pipe
 . elif ${MACHINE_ARCH} == "ia64"
 COPTFLAGS?=-O2 -pipe