diff --git a/slirp/ip6_icmp.c b/slirp/ip6_icmp.c
index 595a62c8d4..bce075913c 100644
--- a/slirp/ip6_icmp.c
+++ b/slirp/ip6_icmp.c
@@ -390,7 +390,7 @@ void icmp6_input(struct mbuf *m)
     int hlen = sizeof(struct ip6);
 
     DEBUG_CALL("icmp6_input");
-    DEBUG_ARG("m = %lx", (long) m);
+    DEBUG_ARG("m = %p", m);
     DEBUG_ARG("m_len = %d", m->m_len);
 
     if (ntohs(ip->ip_pl) < ICMP6_MINLEN) {
diff --git a/slirp/ip6_input.c b/slirp/ip6_input.c
index ac2e3ea882..ab656a0a9d 100644
--- a/slirp/ip6_input.c
+++ b/slirp/ip6_input.c
@@ -31,7 +31,7 @@ void ip6_input(struct mbuf *m)
     }
 
     DEBUG_CALL("ip6_input");
-    DEBUG_ARG("m = %lx", (long)m);
+    DEBUG_ARG("m = %p", m);
     DEBUG_ARG("m_len = %d", m->m_len);
 
     if (m->m_len < sizeof(struct ip6)) {
diff --git a/slirp/ip6_output.c b/slirp/ip6_output.c
index 762cbfe89c..52c88ad691 100644
--- a/slirp/ip6_output.c
+++ b/slirp/ip6_output.c
@@ -19,8 +19,8 @@ int ip6_output(struct socket *so, struct mbuf *m, int fast)
     struct ip6 *ip = mtod(m, struct ip6 *);
 
     DEBUG_CALL("ip6_output");
-    DEBUG_ARG("so = %lx", (long)so);
-    DEBUG_ARG("m = %lx", (long)m);
+    DEBUG_ARG("so = %p", so);
+    DEBUG_ARG("m = %p", m);
 
     /* Fill IPv6 header */
     ip->ip_v = IP6VERSION;
diff --git a/slirp/udp6.c b/slirp/udp6.c
index 473ba1586e..8cdb1892e2 100644
--- a/slirp/udp6.c
+++ b/slirp/udp6.c
@@ -20,7 +20,7 @@ void udp6_input(struct mbuf *m)
     struct sockaddr_in6 lhost;
 
     DEBUG_CALL("udp6_input");
-    DEBUG_ARG("m = %lx", (long)m);
+    DEBUG_ARG("m = %p", m);
 
     if (slirp->restricted) {
         goto bad;
@@ -144,8 +144,8 @@ int udp6_output(struct socket *so, struct mbuf *m,
     struct udphdr *uh;
 
     DEBUG_CALL("udp6_output");
-    DEBUG_ARG("so = %lx", (long)so);
-    DEBUG_ARG("m = %lx", (long)m);
+    DEBUG_ARG("so = %p", so);
+    DEBUG_ARG("m = %p", m);
 
     /* adjust for header */
     m->m_data -= sizeof(struct udphdr);