diff --git a/pym/portage/package/ebuild/config.py b/pym/portage/package/ebuild/config.py
index b1d8f67..3cbf96a 100644
--- a/pym/portage/package/ebuild/config.py
+++ b/pym/portage/package/ebuild/config.py
@@ -1745,6 +1745,7 @@ class config(object):
 		if iuse is not None:
 			iuse = [x.lstrip("+-") for x in iuse.split()]
 		myflags = set()
+		configdict_conf = self.configdict['conf']
 		for curdb in self.uvlist:
 			cur_use_expand = [x for x in use_expand if x in curdb]
 			mysplit = curdb.get("USE", "").split()
@@ -1794,7 +1795,7 @@ class config(object):
 			for var in cur_use_expand:
 				var_lower = var.lower()
 				is_not_incremental = var not in myincrementals
-				if is_not_incremental:
+				if is_not_incremental and curdb is configdict_conf:
 					prefix = var_lower + "_"
 					prefix_len = len(prefix)
 					for x in list(myflags):