diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index e805481eff72..727f4365bcdf 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -112,7 +112,8 @@
 #define RT_FL_TOS(oldflp4) \
 	((oldflp4)->flowi4_tos & (IPTOS_RT_MASK | RTO_ONLINK))
 
-#define IP_MAX_MTU	0xFFF0
+/* IPv4 datagram length is stored into 16bit field (tot_len) */
+#define IP_MAX_MTU	0xFFFF
 
 #define RT_GC_TIMEOUT (300*HZ)
 
@@ -1227,10 +1228,7 @@ static unsigned int ipv4_mtu(const struct dst_entry *dst)
 			mtu = 576;
 	}
 
-	if (mtu > IP_MAX_MTU)
-		mtu = IP_MAX_MTU;
-
-	return mtu;
+	return min_t(unsigned int, mtu, IP_MAX_MTU);
 }
 
 static struct fib_nh_exception *find_exception(struct fib_nh *nh, __be32 daddr)