diff --git a/chapter05/5-1.c b/chapter05/5-1.c
index 96c7552..d4294d2 100644
--- a/chapter05/5-1.c
+++ b/chapter05/5-1.c
@@ -46,8 +46,10 @@ int getint(int *pn)
 	}
 	sign = (c == '-') ? -1 : 1;
 	if (c == '+' || c == '-')
-		if (!isdigit((c = getch()))) /* sign followed by a digit? */
+		if (!isdigit((c = getch()))) { /* sign followed by a digit? */
+            ungetch(c); /* push the non-digit character back */
 			return 0; /* not a number */
+        }
 	for (*pn = 0; isdigit(c); c = getch())
 		*pn = 10 * *pn + (c - '0');
 	*pn *= sign;