diff --git a/pym/portage/checksum.py b/pym/portage/checksum.py
index 73e01b5..7fadc60 100644
--- a/pym/portage/checksum.py
+++ b/pym/portage/checksum.py
@@ -184,10 +184,8 @@ def _perform_md5_merge(x, **kwargs):
 		encoding=_encodings['merge'], errors='strict'), **kwargs)
 
 def perform_all(x, calc_prelink=0):
-	mydict = {}
-	for k in hashfunc_map:
-		mydict[k] = perform_checksum(x, hashfunc_map[k], calc_prelink)[0]
-	return mydict
+	return dict( (k, perform_checksum(x, k, calc_prelink)[0])
+		     for k in hashfunc_map.keys() )
 
 def get_valid_checksum_keys():
 	return list(hashfunc_map)
@@ -301,8 +299,9 @@ def perform_checksum(filename, hashname="MD5", calc_prelink=0):
 				prelink_capable = False
 		try:
 			if hashname not in hashfunc_map:
-				raise portage.exception.DigestException(hashname + \
-					" hash function not available (needs dev-python/pycrypto)")
+				raise portage.exception.DigestException(
+					"%s hash function not available (needs dev-python/pycrypto)"
+						% hashname )
 			myhash, mysize = hashfunc_map[hashname](myfilename)
 		except (OSError, IOError) as e:
 			if e.errno in (errno.ENOENT, errno.ESTALE):