diff --git a/freebsd/sbin/ifconfig/af_inet.c b/freebsd/sbin/ifconfig/af_inet.c
index 3ef6c1a1..7a4acfc9 100644
--- a/freebsd/sbin/ifconfig/af_inet.c
+++ b/freebsd/sbin/ifconfig/af_inet.c
@@ -116,7 +116,7 @@ in_getaddr(const char *s, int which)
 			int masklen;
 			struct sockaddr_in *min = sintab[MASK];
 			*p = '\0';
-			if (!isdigit(*(p + 1)))
+			if (!isdigit((unsigned char)*(p + 1)))
 				errstr = "invalid";
 			else
 				masklen = (int)strtonum(p + 1, 0, 32, &errstr);
diff --git a/freebsd/sbin/ifconfig/ifbridge.c b/freebsd/sbin/ifconfig/ifbridge.c
index eebeebd4..05ebfe31 100644
--- a/freebsd/sbin/ifconfig/ifbridge.c
+++ b/freebsd/sbin/ifconfig/ifbridge.c
@@ -155,7 +155,7 @@ bridge_interfaces(int s, const char *prefix)
 		err(1, "strdup");
 	/* replace the prefix with whitespace */
 	for (p = pad; *p != '\0'; p++) {
-		if(isprint(*p))
+		if(isprint((unsigned char)*p))
 			*p = ' ';
 	}
 
diff --git a/freebsd/sbin/ifconfig/ifgroup.c b/freebsd/sbin/ifconfig/ifgroup.c
index 619c8f74..596a5220 100644
--- a/freebsd/sbin/ifconfig/ifgroup.c
+++ b/freebsd/sbin/ifconfig/ifgroup.c
@@ -52,7 +52,7 @@ setifgroup(const char *group_name, int d, int s, const struct afswtch *rafp)
 	memset(&ifgr, 0, sizeof(ifgr));
 	strlcpy(ifgr.ifgr_name, name, IFNAMSIZ);
 
-	if (group_name[0] && isdigit(group_name[strlen(group_name) - 1]))
+	if (group_name[0] && isdigit((unsigned char)group_name[strlen(group_name) - 1]))
 		errx(1, "setifgroup: group names may not end in a digit");
 
 	if (strlcpy(ifgr.ifgr_group, group_name, IFNAMSIZ) >= IFNAMSIZ)
@@ -70,7 +70,7 @@ unsetifgroup(const char *group_name, int d, int s, const struct afswtch *rafp)
 	memset(&ifgr, 0, sizeof(ifgr));
 	strlcpy(ifgr.ifgr_name, name, IFNAMSIZ);
 
-	if (group_name[0] && isdigit(group_name[strlen(group_name) - 1]))
+	if (group_name[0] && isdigit((unsigned char)group_name[strlen(group_name) - 1]))
 		errx(1, "unsetifgroup: group names may not end in a digit");
 
 	if (strlcpy(ifgr.ifgr_group, group_name, IFNAMSIZ) >= IFNAMSIZ)