diff --git a/share/mk/bsd.obj.mk b/share/mk/bsd.obj.mk
index b648222d8979..71f46605d37c 100644
--- a/share/mk/bsd.obj.mk
+++ b/share/mk/bsd.obj.mk
@@ -43,7 +43,7 @@
 #		create build directory.
 #
 
-.if defined(MAKEOBJDIRPREFIX)
+.if defined(MAKEOBJDIRPREFIX) && !empty(MAKEOBJDIRPREFIX)
 CANONICALOBJDIR:=${MAKEOBJDIRPREFIX}${.CURDIR}
 .else
 CANONICALOBJDIR:=/usr/obj${.CURDIR}