diff --git a/pym/portage/__init__.py b/pym/portage/__init__.py
index d78491c..0475b1b 100644
--- a/pym/portage/__init__.py
+++ b/pym/portage/__init__.py
@@ -3,7 +3,6 @@
 # Distributed under the terms of the GNU General Public License v2
 # $Id$
 
-
 VERSION="$Rev$"[6:-2] + "-svn"
 
 # ===========================================================================
@@ -110,7 +109,6 @@ except ImportError, e:
 	sys.stderr.write("    "+str(e)+"\n\n")
 	raise
 
-
 try:
 	import portage._selinux as selinux
 except OSError, e:
@@ -2338,6 +2336,7 @@ class config(object):
 		for k in pkg_configdict:
 			if k != 'USE':
 				env_configdict.pop(k, None)
+		del k
 
 		lazy_vars = self._lazy_vars(built_use, self)
 		env_configdict.addLazySingleton('ACCEPT_LICENSE',
@@ -2391,32 +2390,36 @@ class config(object):
 		lazy_use_expand = self._lazy_use_expand(use, self.usemask,
 			iuse_implicit, use_expand_split, self._use_expand_dict)
 
-		use_expand_iuses = {}
-		for x in iuse_implicit:
-			x_split = x.split('_')
-			if len(x_split) == 1:
-				continue
-			for i in xrange(len(x_split) - 1):
-				k = '_'.join(x_split[:i+1])
-				if k in use_expand_split:
-					v = use_expand_iuses.get(k)
-					if v is None:
-						v = set()
-						use_expand_iuses[k] = v
-					v.add(x)
-					break
 
 		# If it's not in IUSE, variable content is allowed
 		# to pass through if it is defined somewhere.  This
 		# allows packages that support LINGUAS but don't
 		# declare it in IUSE to use the variable outside of the
 		# USE_EXPAND context.
-		for k, use_expand_iuse in use_expand_iuses.iteritems():
-			if k + '_*' in use:
-				use.update( x for x in use_expand_iuse if x not in usemask )
-			k = k.upper()
-			self.configdict['env'].addLazySingleton(k,
-				lazy_use_expand.__getitem__, k)
+
+		iuse_implicit = sorted( x for x in iuse_implicit if x.find('_') != -1 )
+		use_expand_iuse = set()
+		k = None
+		k_len = None
+		for x in iuse_implicit:
+			if not k or x[:k_len] != k:
+				if k:
+					if k + '_*' in use:
+						use.update( use_expand_iuse.difference(usemask) )
+					k = k.upper()
+					self.configdict['env'].addLazySingleton(k,
+						lazy_use_expand.__getitem__, k)
+					k = None
+					k_len = None
+					use_expand_iuse = set()
+				l = [y for y in use_expand_split if x[:len(y)] == y]
+				if l:
+					k = l[0]
+					k_len = len(k)
+				else:
+					continue
+			use_expand_iuse.add(x)
+		del k, k_len, x, use_expand_iuse
 
 		# Filtered for the ebuild environment. Store this in a separate
 		# attribute since we still want to be able to see global USE
@@ -2860,7 +2863,6 @@ class config(object):
 			# an incremental!
 			myincrementals.remove("USE")
 
-
 		mydbs = self.configlist[:-1]
 		mydbs.append(self.backupenv)
 
@@ -6362,7 +6364,6 @@ def doebuild(myebuild, mydo, myroot, mysettings, debug=0, listonly=0,
 			# so do not check them again.
 			checkme = []
 
-
 		if not emerge_skip_distfiles and \
 			need_distfiles and not fetch(
 			fetchme, mysettings, listonly=listonly, fetchonly=fetchonly):
@@ -7223,7 +7224,6 @@ def dep_zapdeps(unreduced, reduced, myroot, use_binaries=0, trees=None):
 
 	assert(False) # This point should not be reachable
 
-
 def dep_expand(mydep, mydb=None, use_cache=1, settings=None):
 	if not len(mydep):
 		return mydep
@@ -7702,7 +7702,6 @@ def getmaskingstatus(mycpv, settings=None, portdb=None):
 
 	return rValue
 
-
 auxdbkeys=[
   'DEPEND',    'RDEPEND',   'SLOT',      'SRC_URI',
 	'RESTRICT',  'HOMEPAGE',  'LICENSE',   'DESCRIPTION',
@@ -8400,7 +8399,6 @@ def init_legacy_globals():
 
 	root = settings["ROOT"]
 
-
 	# ========================================================================
 	# COMPATIBILITY
 	# These attributes should not be used