diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index c30245d..a2ddf3e 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -5725,7 +5725,7 @@
             }
             else {
                 WRITECHAR('\\');
-                WRITECHAR(s[-1]);
+                WRITECHAR((unsigned char)s[-1]);
             }
             break;
         }