diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index 89a47b35905dcc6e1c3bb94b0db7c6a32a61e8fc..cb982a61536fade811908a18e6119f513914741e 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -459,28 +459,22 @@ static u32 esp4_get_mtu(struct xfrm_state *x, int mtu)
 	struct esp_data *esp = x->data;
 	u32 blksize = ALIGN(crypto_aead_blocksize(esp->aead), 4);
 	u32 align = max_t(u32, blksize, esp->padlen);
-	u32 rem;
-
-	mtu -= x->props.header_len + crypto_aead_authsize(esp->aead);
-	rem = mtu & (align - 1);
-	mtu &= ~(align - 1);
+	unsigned int net_adj;
 
 	switch (x->props.mode) {
-	case XFRM_MODE_TUNNEL:
-		break;
-	default:
 	case XFRM_MODE_TRANSPORT:
-		/* The worst case */
-		mtu -= blksize - 4;
-		mtu += min_t(u32, blksize - 4, rem);
-		break;
 	case XFRM_MODE_BEET:
-		/* The worst case. */
-		mtu += min_t(u32, IPV4_BEET_PHMAXLEN, rem);
+		net_adj = sizeof(struct iphdr);
 		break;
+	case XFRM_MODE_TUNNEL:
+		net_adj = 0;
+		break;
+	default:
+		BUG();
 	}
 
-	return mtu - 2;
+	return ((mtu - x->props.header_len - crypto_aead_authsize(esp->aead) -
+		 net_adj) & ~(align - 1)) + (net_adj - 2);
 }
 
 static void esp4_err(struct sk_buff *skb, u32 info)
diff --git a/net/ipv6/esp6.c b/net/ipv6/esp6.c
index 1e62b7557b00e1e0897f480d9391d018dfd01dcb..db1521fcda5b3fd182a3068c9b86d5161e5e4d56 100644
--- a/net/ipv6/esp6.c
+++ b/net/ipv6/esp6.c
@@ -413,19 +413,15 @@ static u32 esp6_get_mtu(struct xfrm_state *x, int mtu)
 	struct esp_data *esp = x->data;
 	u32 blksize = ALIGN(crypto_aead_blocksize(esp->aead), 4);
 	u32 align = max_t(u32, blksize, esp->padlen);
-	u32 rem;
+	unsigned int net_adj;
 
-	mtu -= x->props.header_len + crypto_aead_authsize(esp->aead);
-	rem = mtu & (align - 1);
-	mtu &= ~(align - 1);
-
-	if (x->props.mode != XFRM_MODE_TUNNEL) {
-		u32 padsize = ((blksize - 1) & 7) + 1;
-		mtu -= blksize - padsize;
-		mtu += min_t(u32, blksize - padsize, rem);
-	}
+	if (x->props.mode != XFRM_MODE_TUNNEL)
+		net_adj = sizeof(struct ipv6hdr);
+	else
+		net_adj = 0;
 
-	return mtu - 2;
+	return ((mtu - x->props.header_len - crypto_aead_authsize(esp->aead) -
+		 net_adj) & ~(align - 1)) + (net_adj - 2);
 }
 
 static void esp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,