diff --git a/Objects/frameobject.c b/Objects/frameobject.c
index 7815f92..062e906 100644
--- a/Objects/frameobject.c
+++ b/Objects/frameobject.c
@@ -128,7 +128,7 @@
 
 	/* Find the bytecode offset for the start of the given line, or the
 	 * first code-owning line after it. */
-	PyString_AsStringAndSize(f->f_code->co_lnotab, &lnotab, &lnotab_len);
+	PyBytes_AsStringAndSize(f->f_code->co_lnotab, &lnotab, &lnotab_len);
 	addr = 0;
 	line = f->f_code->co_firstlineno;
 	new_lasti = -1;
@@ -151,7 +151,7 @@
 	}
 
 	/* We're now ready to look at the bytecode. */
-	PyString_AsStringAndSize(f->f_code->co_code, (char **)&code, &code_len);
+	PyBytes_AsStringAndSize(f->f_code->co_code, (char **)&code, &code_len);
 	min_addr = MIN(new_lasti, f->f_lasti);
 	max_addr = MAX(new_lasti, f->f_lasti);