Index: Mk/bsd.options.mk
===================================================================
--- Mk/bsd.options.mk	(revision 332092)
+++ Mk/bsd.options.mk	(working copy)
@@ -387,7 +387,7 @@
 .    if defined(${opt}_USE)
 .      for option in ${${opt}_USE}
 _u=		${option:C/=.*//g}
-USE_${_u:U}+=	${option:C/.*=//g}
+USE_${_u:U}+=	${option:C/.*=//g:C/^"//:C/"$$//}
 .      endfor
 .    endif
 .    if defined(${opt}_CONFIGURE_ENABLE)