Index: Mk/bsd.port.mk
===================================================================
--- Mk/bsd.port.mk	(revision 384088)
+++ Mk/bsd.port.mk	(working copy)
@@ -1441,9 +1448,8 @@ DESTDIRNAME?=	DESTDIR
 # Loading features
 .for f in ${USES}
 _f:=		${f:C/\:.*//}
-.if !defined(${_f}_ARGS)
-${_f}_ARGS:=	${f:C/^[^\:]*(\:|\$)//:S/,/ /g}
-.endif
+${_f}_ARGS+=	${f:C/^[^\:]*(\:|\$)//:S/,/ /g}
+${_f}_ARGS:=	${${_f}_ARGS:O:u}
 .endfor
 .for f in ${USES}
 .include "${USESDIR}/${f:C/\:.*//}.mk"
Index: Mk/Uses/compiler.mk
===================================================================
--- Mk/Uses/compiler.mk	(revision 384088)
+++ Mk/Uses/compiler.mk	(working copy)
@@ -36,26 +36,41 @@ compiler_ARGS=	env
 
 VALID_ARGS=	c++11-lib c++11-lang c11 features openmp env nestedfct c++0x gcc-c++11-lib
 
-.if ${compiler_ARGS} == gcc-c++11-lib
+.if ${compiler_ARGS:Mgcc-c++11-lib}
 _COMPILER_ARGS+=	features gcc-c++11-lib
-.elif ${compiler_ARGS} == c++11-lib
+.endif
+.if ${compiler_ARGS:Mc++11-lib}
 _COMPILER_ARGS+=	features c++11-lib
-.elif ${compiler_ARGS} == c++0x
+.endif
+.if ${compiler_ARGS:Mc++0x}
 _COMPILER_ARGS+=	features c++0x
-.elif ${compiler_ARGS} == c++11-lang
+.endif
+.if ${compiler_ARGS:Mc++11-lang}
 _COMPILER_ARGS+=	features c++11-lang
-.elif ${compiler_ARGS} == c11
+.endif
+.if ${compiler_ARGS:Mc11}
 _COMPILER_ARGS+=	features c11
-.elif ${compiler_ARGS} == features
+.endif
+.if ${compiler_ARGS:Mfeatures}
 _COMPILER_ARGS+=	features
-.elif ${compiler_ARGS} == env
+.endif
+.if ${compiler_ARGS:Menv}
 _COMPILER_ARGS+=	env
-.elif ${compiler_ARGS} == openmp
+.endif
+.if ${compiler_ARGS:Mopenmp}
 _COMPILER_ARGS+=	env openmp
-.elif ${compiler_ARGS} == nestedfct
+.endif
+.if ${compiler_ARGS:Mnestedfct}
 _COMPILER_ARGS+=	env nestedfct
-.else
-IGNORE=	Invalid argument "${compiler_ARGS}", valid arguments are: ${VALID_ARGS}
+.endif
+
+INVALID_ARGS=	${compiler_ARGS}
+.for v in ${VALID_ARGS}
+INVALID_ARGS:=	${INVALID_ARGS:N${v}}
+.endfor
+
+.if !empty(INVALID_ARGS)
+IGNORE=	Invalid argument "${INVALID_ARGS}", valid arguments are: ${VALID_ARGS}
 _COMPILER_ARGS=	#
 .endif