diff --git a/Lib/modulefinder.py b/Lib/modulefinder.py
index 1dbc5bb..cd9906c 100644
--- a/Lib/modulefinder.py
+++ b/Lib/modulefinder.py
@@ -16,12 +16,13 @@
     # remain compatible with Python  < 2.3
     READ_MODE = "r"
 
-LOAD_CONST = chr(dis.opname.index('LOAD_CONST'))
-IMPORT_NAME = chr(dis.opname.index('IMPORT_NAME'))
-STORE_NAME = chr(dis.opname.index('STORE_NAME'))
-STORE_GLOBAL = chr(dis.opname.index('STORE_GLOBAL'))
+# XXX Clean up once str8's cstor matches bytes.
+LOAD_CONST = str8(chr(dis.opname.index('LOAD_CONST')))
+IMPORT_NAME = str8(chr(dis.opname.index('IMPORT_NAME')))
+STORE_NAME = str8(chr(dis.opname.index('STORE_NAME')))
+STORE_GLOBAL = str8(chr(dis.opname.index('STORE_GLOBAL')))
 STORE_OPS = [STORE_NAME, STORE_GLOBAL]
-HAVE_ARGUMENT = chr(dis.HAVE_ARGUMENT)
+HAVE_ARGUMENT = str8(chr(dis.HAVE_ARGUMENT))
 
 # Modulefinder does a good job at simulating Python's, but it can not
 # handle __path__ modifications packages make at runtime.  Therefore there
@@ -367,7 +368,7 @@
         consts = co.co_consts
         LOAD_LOAD_AND_IMPORT = LOAD_CONST + LOAD_CONST + IMPORT_NAME
         while code:
-            c = chr(code[0])
+            c = str8(chr(code[0]))
             if c in STORE_OPS:
                 oparg, = unpack('<H', code[1:3])
                 yield "store", (names[oparg],)