@@ -974,17 +974,16 @@
 	if (string[0] == '-')
 		i++;
 
 	for (; i < length; i++) {
 		if (string[i] >= '0' && string[i] <= '9') {
-			intmax_t newnum = (num * 10) + (string[i] - '0');
-
-			if (newnum < num)
+			if (INTMAX_MAX / 10 < num ||
+			    INTMAX_MAX - num * 10 < string[i] - '0')
 				@throw [OFOutOfRangeException
 				    newWithClass: isa];
 
-			num = newnum;
+			num = (num * 10) + (string[i] - '0');
 		} else
 			@throw [OFInvalidEncodingException newWithClass: isa];
 	}
 
 	if (string[0] == '-')