diff --git a/Objects/frameobject.c b/Objects/frameobject.c
index a494992..664dc2b 100644
--- a/Objects/frameobject.c
+++ b/Objects/frameobject.c
@@ -130,8 +130,10 @@
 	else {
 		/* Find the bytecode offset for the start of the given
 		 * line, or the first code-owning line after it. */
+		char *tmp;
 		PyBytes_AsStringAndSize(f->f_code->co_lnotab,
-					&(char*)lnotab, &lnotab_len);
+					&tmp, &lnotab_len);
+		lnotab = (unsigned char *) tmp;
 		addr = 0;
 		line = f->f_code->co_firstlineno;
 		new_lasti = -1;