diff --git a/slirp/if.c b/slirp/if.c
index 6feca55e35..67a7b6ff82 100644
--- a/slirp/if.c
+++ b/slirp/if.c
@@ -8,8 +8,6 @@
 #include <slirp.h>
 
 int     if_queued = 0;                  /* Number of packets queued so far */
-int     if_thresh = 10;                 /* Number of packets queued before we start sending
-					 * (to prevent allocing too many mbufs) */
 
 struct  mbuf if_fastq;                  /* fast queue (for interactive data) */
 struct  mbuf if_batchq;                 /* queue for non-interactive data */
diff --git a/slirp/if.h b/slirp/if.h
index ea96696b9f..bed7152fe3 100644
--- a/slirp/if.h
+++ b/slirp/if.h
@@ -33,8 +33,6 @@
 #endif
 
 extern int	if_queued;	/* Number of packets queued so far */
-extern int	if_thresh;	/* Number of packets queued before we start sending
-				 * (to prevent allocing too many mbufs) */
 
 extern	struct mbuf if_fastq;                  /* fast queue (for interactive data) */
 extern	struct mbuf if_batchq;                 /* queue for non-interactive data */
diff --git a/slirp/ip_icmp.c b/slirp/ip_icmp.c
index b589651cad..d1da0a2fcd 100644
--- a/slirp/ip_icmp.c
+++ b/slirp/ip_icmp.c
@@ -42,8 +42,8 @@ struct icmpstat icmpstat;
 #endif
 
 /* The message sent when emulating PING */
-/* Be nice and tell them it's just a psuedo-ping packet */
-char icmp_ping_msg[] = "This is a psuedo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
+/* Be nice and tell them it's just a pseudo-ping packet */
+const char icmp_ping_msg[] = "This is a pseudo-PING packet used by Slirp to emulate ICMP ECHO-REQUEST packets.\n";
 
 /* list of actions for icmp_error() on RX of an icmp message */
 static const int icmp_flush[19] = {
diff --git a/slirp/ip_output.c b/slirp/ip_output.c
index 86cf3a0339..a8a6067bda 100644
--- a/slirp/ip_output.c
+++ b/slirp/ip_output.c
@@ -46,6 +46,10 @@
 
 u_int16_t ip_id;
 
+/* Number of packets queued before we start sending
+ * (to prevent allocing too many mbufs) */
+#define IF_THRESH 10
+
 /*
  * IP output.  The packet in mbuf chain m contains a skeletal IP
  * header (with len, off, ttl, proto, tos, src, dst).
@@ -87,7 +91,7 @@ ip_output(so, m0)
 	 *      the packet or packet fragments
 	 */
 	/* XXX Hmmm... */
-/*	if (if_queued > if_thresh && towrite <= 0) {
+/*	if (if_queued > IF_THRESH && towrite <= 0) {
  *		error = ENOBUFS;
  *		goto bad;
  *	}
diff --git a/slirp/slirp.h b/slirp/slirp.h
index 7b0e968f8f..a28e5feacb 100644
--- a/slirp/slirp.h
+++ b/slirp/slirp.h
@@ -264,8 +264,6 @@ void if_start _P((struct ttys *));
 
 void lprint _P((const char *, ...));
 
-extern int do_echo;
-
 #if SIZEOF_CHAR_P == 4
 # define insque_32 insque
 # define remque_32 remque
diff --git a/slirp/tcp_subr.c b/slirp/tcp_subr.c
index d5ba21f17a..7d71270542 100644
--- a/slirp/tcp_subr.c
+++ b/slirp/tcp_subr.c
@@ -592,7 +592,9 @@ tcp_tos(so)
 	return 0;
 }
 
+#if 0
 int do_echo = -1;
+#endif
 
 /*
  * Emulate programs that try and connect to us