diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 1dd3a85..3ef9c9b 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -9648,7 +9648,7 @@
                     c = *fmt++;
                     if (c < '0' || c > '9')
                         break;
-                    if ((width*10) / 10 != width) {
+                    if (width > (PY_SSIZE_T_MAX - ((int)c - '0')) / 10) {
                         PyErr_SetString(PyExc_ValueError,
                                         "width too big");
                         goto onError;
@@ -9683,7 +9683,7 @@
                         c = *fmt++;
                         if (c < '0' || c > '9')
                             break;
-                        if ((prec*10) / 10 != prec) {
+                        if (prec > (INT_MAX - ((int)c - '0')) / 10) {
                             PyErr_SetString(PyExc_ValueError,
                                             "prec too big");
                             goto onError;