diff --git a/BasiliskII/src/slirp/mbuf.c b/BasiliskII/src/slirp/mbuf.c
index 86bb4f40..2b53bc3e 100644
--- a/BasiliskII/src/slirp/mbuf.c
+++ b/BasiliskII/src/slirp/mbuf.c
@@ -15,6 +15,7 @@
  * the flags
  */
 
+#include <stdlib.h>
 #include <slirp.h>
 
 struct	mbuf *mbutl;
diff --git a/BasiliskII/src/slirp/misc.c b/BasiliskII/src/slirp/misc.c
index 233c965f..af00bff5 100644
--- a/BasiliskII/src/slirp/misc.c
+++ b/BasiliskII/src/slirp/misc.c
@@ -6,6 +6,7 @@
  */
 
 #define WANT_SYS_IOCTL_H
+#include <stdlib.h>
 #include <slirp.h>
 
 u_int curtime, time_fasttimo, last_slowtimo, detach_time;
diff --git a/BasiliskII/src/slirp/sbuf.c b/BasiliskII/src/slirp/sbuf.c
index d6726c94..2d078f38 100644
--- a/BasiliskII/src/slirp/sbuf.c
+++ b/BasiliskII/src/slirp/sbuf.c
@@ -5,6 +5,7 @@
  * terms and conditions of the copyright.
  */
 
+#include <stdlib.h>
 #include <slirp.h>
 
 /* Done as a macro in socket.h */
diff --git a/BasiliskII/src/slirp/socket.c b/BasiliskII/src/slirp/socket.c
index f2afd068..ca766a40 100644
--- a/BasiliskII/src/slirp/socket.c
+++ b/BasiliskII/src/slirp/socket.c
@@ -6,6 +6,7 @@
  */
 
 #define WANT_SYS_IOCTL_H
+#include <stdlib.h>
 #include <slirp.h>
 #include "ip_icmp.h"
 #include "main.h"
diff --git a/BasiliskII/src/slirp/tcp_subr.c b/BasiliskII/src/slirp/tcp_subr.c
index 5e87a67a..cace614d 100644
--- a/BasiliskII/src/slirp/tcp_subr.c
+++ b/BasiliskII/src/slirp/tcp_subr.c
@@ -43,6 +43,7 @@
  */
 
 #define WANT_SYS_IOCTL_H
+#include <stdlib.h>
 #include <slirp.h>
 
 /* patchable/settable parameters for tcp */