diff --git a/Python/peephole.c b/Python/peephole.c
index db5ca33..30789e4 100644
--- a/Python/peephole.c
+++ b/Python/peephole.c
@@ -325,15 +325,15 @@
 		goto exitUnchanged;
 
 	/* Bypass optimization when the lineno table is too complex */
-	assert(PyString_Check(lineno_obj));
-	lineno = (unsigned char*)PyString_AS_STRING(lineno_obj);
-	tabsiz = PyString_GET_SIZE(lineno_obj);
+	assert(PyBytes_Check(lineno_obj));
+	lineno = (unsigned char*)PyBytes_AS_STRING(lineno_obj);
+	tabsiz = PyBytes_GET_SIZE(lineno_obj);
 	if (memchr(lineno, 255, tabsiz) != NULL)
 		goto exitUnchanged;
 
 	/* Avoid situations where jump retargeting could overflow */
-	assert(PyString_Check(code));
-	codelen = PyString_GET_SIZE(code);
+	assert(PyBytes_Check(code));
+	codelen = PyBytes_GET_SIZE(code);
 	if (codelen > 32700)
 		goto exitUnchanged;
 
@@ -342,7 +342,7 @@
 	if (codestr == NULL)
 		goto exitUnchanged;
 	codestr = (unsigned char *)memcpy(codestr, 
-					  PyString_AS_STRING(code), codelen);
+					  PyBytes_AS_STRING(code), codelen);
 
 	/* Verify that RETURN_VALUE terminates the codestring.	This allows
 	   the various transformation patterns to look ahead several
@@ -632,7 +632,7 @@
 	}
 	assert(h + nops == codelen);
 
-	code = PyString_FromStringAndSize((char *)codestr, h);
+	code = PyBytes_FromStringAndSize((char *)codestr, h);
 	PyMem_Free(addrmap);
 	PyMem_Free(codestr);
 	PyMem_Free(blocks);