diff --git a/BasiliskII/src/slirp/bootp.h b/BasiliskII/src/slirp/bootp.h
index e48f53f3..5c2e62ab 100644
--- a/BasiliskII/src/slirp/bootp.h
+++ b/BasiliskII/src/slirp/bootp.h
@@ -90,6 +90,10 @@
 #define BOOTP_VENDOR_LEN	64
 #define DHCP_OPT_LEN		312
 
+#ifdef PRAGMA_PACK_SUPPORTED
+#pragma pack(1)
+#endif
+
 struct bootp_t {
     struct ip ip;
     struct udphdr udp;
@@ -108,6 +112,10 @@ struct bootp_t {
     uint8_t bp_sname[64];
     uint8_t bp_file[128];
     uint8_t bp_vend[DHCP_OPT_LEN];
-};
+} PACKED__;
+
+#ifdef PRAGMA_PACK_SUPPORTED
+#pragma pack(0)
+#endif
 
 void bootp_input(struct mbuf *m);
diff --git a/BasiliskII/src/slirp/ip.h b/BasiliskII/src/slirp/ip.h
index 8280e55b..07286a56 100644
--- a/BasiliskII/src/slirp/ip.h
+++ b/BasiliskII/src/slirp/ip.h
@@ -80,6 +80,10 @@ typedef u_int32_t n_long;                 /* long as received from the net */
  * pragmatically since otherwise unsigned comparisons can result
  * against negative integers quite easily, and fail in subtle ways.
  */
+#ifdef PRAGMA_PACK_SUPPORTED
+#pragma pack(1)
+#endif
+
 struct ip {
 #ifdef WORDS_BIGENDIAN
 	u_int ip_v:4,			/* version */
@@ -99,7 +103,11 @@ struct ip {
 	u_int8_t ip_p;			/* protocol */
 	u_int16_t	ip_sum;			/* checksum */
 	struct	in_addr ip_src,ip_dst;	/* source and dest address */
-};
+} PACKED__;
+
+#ifdef PRAGMA_PACK_SUPPORTED
+#pragma pack(0)
+#endif
 
 #define	IP_MAXPACKET	65535		/* maximum packet size */
 
@@ -143,6 +151,10 @@ struct ip {
 /*
  * Time stamp option structure.
  */
+#ifdef PRAGMA_PACK_SUPPORTED
+#pragma pack(1)
+#endif
+
 struct	ip_timestamp {
 	u_int8_t	ipt_code;		/* IPOPT_TS */
 	u_int8_t	ipt_len;		/* size of structure (variable) */
@@ -161,7 +173,11 @@ struct	ip_timestamp {
 			n_long ipt_time;
 		} ipt_ta[1];
 	} ipt_timestamp;
-};
+} PACKED__;
+
+#ifdef PRAGMA_PACK_SUPPORTED
+#pragma pack(0)
+#endif
 
 /* flag bits for ipt_flg */
 #define	IPOPT_TS_TSONLY		0		/* timestamps only */
@@ -208,6 +224,10 @@ typedef caddr32_t ipasfragp_32;
 /*
  * Overlay for ip header used by other protocols (tcp, udp).
  */
+#ifdef PRAGMA_PACK_SUPPORTED
+#pragma pack(1)
+#endif
+
 struct ipovly {
 	caddr32_t	ih_next, ih_prev;	/* for protocol sequence q's */
 	u_int8_t	ih_x1;			/* (unused) */
@@ -215,7 +235,11 @@ struct ipovly {
 	int16_t	ih_len;			/* protocol length */
 	struct	in_addr ih_src;		/* source internet address */
 	struct	in_addr ih_dst;		/* destination internet address */
-};
+} PACKED__;
+
+#ifdef PRAGMA_PACK_SUPPORTED
+#pragma pack(0)
+#endif
 
 /*
  * Ip reassembly queue structure.  Each fragment
diff --git a/BasiliskII/src/slirp/ip_icmp.h b/BasiliskII/src/slirp/ip_icmp.h
index 8c9b5a1b..bf6c2cfa 100644
--- a/BasiliskII/src/slirp/ip_icmp.h
+++ b/BasiliskII/src/slirp/ip_icmp.h
@@ -47,6 +47,10 @@ typedef u_int32_t n_time;
 /*
  * Structure of an icmp header.
  */
+#ifdef PRAGMA_PACK_SUPPORTED
+#pragma pack(1)
+#endif
+
 struct icmp {
 	u_char	icmp_type;		/* type of message, see below */
 	u_char	icmp_code;		/* type sub code */
@@ -92,7 +96,11 @@ struct icmp {
 #define	icmp_ip		icmp_dun.id_ip.idi_ip
 #define	icmp_mask	icmp_dun.id_mask
 #define	icmp_data	icmp_dun.id_data
-};
+} PACKED__;
+
+#ifdef PRAGMA_PACK_SUPPORTED
+#pragma pack(0)
+#endif
 
 /*
  * Lower bounds on packet lengths for various types.
diff --git a/BasiliskII/src/slirp/slirp.c b/BasiliskII/src/slirp/slirp.c
index 4a35e724..37f2460a 100644
--- a/BasiliskII/src/slirp/slirp.c
+++ b/BasiliskII/src/slirp/slirp.c
@@ -595,7 +595,7 @@ void slirp_input(const uint8_t *pkt, int pkt_len)
     if (pkt_len < ETH_HLEN)
         return;
     
-    proto = ntohs(*(uint16_t *)(pkt + 12));
+    proto = (pkt[12] << 8) | pkt[13];
     switch(proto) {
     case ETH_P_ARP:
         arp_input(pkt, pkt_len);
diff --git a/BasiliskII/src/slirp/slirp.h b/BasiliskII/src/slirp/slirp.h
index 23f2bdda..698a2b3f 100644
--- a/BasiliskII/src/slirp/slirp.h
+++ b/BasiliskII/src/slirp/slirp.h
@@ -195,6 +195,15 @@ int inet_aton _P((const char *cp, struct in_addr *ia));
 
 #include "debug.h"
 
+#if defined __GNUC__
+#define PACKED__ __attribute__ ((packed))
+#elif defined __sgi
+#define PRAGMA_PACK_SUPPORTED 1
+#define PACKED__
+#else
+#error "Packed attribute or pragma shall be supported"
+#endif
+
 #include "ip.h"
 #include "tcp.h"
 #include "tcp_timer.h"
diff --git a/BasiliskII/src/slirp/tcp.h b/BasiliskII/src/slirp/tcp.h
index 3e0b4dd8..8a62bc5f 100644
--- a/BasiliskII/src/slirp/tcp.h
+++ b/BasiliskII/src/slirp/tcp.h
@@ -53,6 +53,10 @@ extern struct socket *tcp_last_so;
  * TCP header.
  * Per RFC 793, September, 1981.
  */
+#ifdef PRAGMA_PACK_SUPPORTED
+#pragma pack(1)
+#endif
+
 struct tcphdr {
 	u_int16_t	th_sport;		/* source port */
 	u_int16_t	th_dport;		/* destination port */
@@ -75,7 +79,11 @@ struct tcphdr {
 	u_int16_t	th_win;			/* window */
 	u_int16_t	th_sum;			/* checksum */
 	u_int16_t	th_urp;			/* urgent pointer */
-};
+} PACKED__;
+
+#ifdef PRAGMA_PACK_SUPPORTED
+#pragma pack(0)
+#endif
 
 #include "tcp_var.h"
 
diff --git a/BasiliskII/src/slirp/tftp.h b/BasiliskII/src/slirp/tftp.h
index f0560b6a..f89e0393 100644
--- a/BasiliskII/src/slirp/tftp.h
+++ b/BasiliskII/src/slirp/tftp.h
@@ -12,6 +12,10 @@
 
 #define TFTP_FILENAME_MAX 512
 
+#ifdef PRAGMA_PACK_SUPPORTED
+#pragma pack(1)
+#endif
+
 struct tftp_t {
   struct ip ip;
   struct udphdr udp;
@@ -27,6 +31,10 @@ struct tftp_t {
     } tp_error;
     u_int8_t tp_buf[512 + 2];
   } x;
-};
+} PACKED__;
+
+#ifdef PRAGMA_PACK_SUPPORTED
+#pragma pack(0)
+#endif
 
 void tftp_input(struct mbuf *m);
diff --git a/BasiliskII/src/slirp/udp.h b/BasiliskII/src/slirp/udp.h
index 24c11bbf..61053c23 100644
--- a/BasiliskII/src/slirp/udp.h
+++ b/BasiliskII/src/slirp/udp.h
@@ -46,12 +46,20 @@ extern struct socket *udp_last_so;
  * Udp protocol header.
  * Per RFC 768, September, 1981.
  */
+#ifdef PRAGMA_PACK_SUPPORTED
+#pragma pack(1)
+#endif
+
 struct udphdr {
 	u_int16_t	uh_sport;		/* source port */
 	u_int16_t	uh_dport;		/* destination port */
 	int16_t	uh_ulen;		/* udp length */
 	u_int16_t	uh_sum;			/* udp checksum */
-};
+} PACKED__;
+
+#ifdef PRAGMA_PACK_SUPPORTED
+#pragma pack(0)
+#endif
 
 /*
  * UDP kernel structures and variables.