diff --git a/sys/conf/kern.pre.mk b/sys/conf/kern.pre.mk
index 4c167ca1f29c..232d88b69e82 100644
--- a/sys/conf/kern.pre.mk
+++ b/sys/conf/kern.pre.mk
@@ -186,7 +186,7 @@ SYSTEM_DEP+= ${LDSCRIPT}
 MKMODULESENV+=	MAKEOBJDIRPREFIX=${.OBJDIR}/modules KMODDIR=${KODIR}
 MKMODULESENV+=	MACHINE_CPUARCH=${MACHINE_CPUARCH}
 MKMODULESENV+=	MACHINE=${MACHINE} MACHINE_ARCH=${MACHINE_ARCH}
-MKMODULESENV+=	MODULES_EXTRA=${MODULES_EXTRA} WITHOUT_MODULES=${WITHOUT_MODULES}
+MKMODULESENV+=	MODULES_EXTRA="${MODULES_EXTRA}" WITHOUT_MODULES="${WITHOUT_MODULES}"
 .if (${KERN_IDENT} == LINT)
 MKMODULESENV+=	ALL_MODULES=LINT
 .endif