diff --git a/libpcap/config.h.in b/libpcap/config.h.in
index 403cbfa7b..3e3c6ad24 100644
--- a/libpcap/config.h.in
+++ b/libpcap/config.h.in
@@ -128,6 +128,9 @@
 /* Define to 1 if you have the `strlcpy' function. */
 #undef HAVE_STRLCPY
 
+/* Define to 1 if the system has the type `struct BPF_TIMEVAL'. */
+#undef HAVE_STRUCT_BPF_TIMEVAL
+
 /* Define to 1 if the system has the type `struct ether_addr'. */
 #undef HAVE_STRUCT_ETHER_ADDR
 
diff --git a/libpcap/configure b/libpcap/configure
index 832369281..3727767a0 100755
--- a/libpcap/configure
+++ b/libpcap/configure
@@ -7240,6 +7240,129 @@ $as_echo "no" >&6; }
 fi
 
 rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+	    #
+	    # Check whether we have struct BPF_TIMEVAL.
+	    #
+	    { $as_echo "$as_me:$LINENO: checking for struct BPF_TIMEVAL" >&5
+$as_echo_n "checking for struct BPF_TIMEVAL... " >&6; }
+if test "${ac_cv_type_struct_BPF_TIMEVAL+set}" = set; then
+  $as_echo_n "(cached) " >&6
+else
+  ac_cv_type_struct_BPF_TIMEVAL=no
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#ifdef HAVE_SYS_IOCCOM_H
+#include <sys/ioccom.h>
+#endif
+#include <net/bpf.h>
+
+
+int
+main ()
+{
+if (sizeof (struct BPF_TIMEVAL))
+       return 0;
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:$LINENO: $ac_try_echo\""
+$as_echo "$ac_try_echo") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#ifdef HAVE_SYS_IOCCOM_H
+#include <sys/ioccom.h>
+#endif
+#include <net/bpf.h>
+
+
+int
+main ()
+{
+if (sizeof ((struct BPF_TIMEVAL)))
+	  return 0;
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:$LINENO: $ac_try_echo\""
+$as_echo "$ac_try_echo") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  :
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	ac_cv_type_struct_BPF_TIMEVAL=yes
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:$LINENO: result: $ac_cv_type_struct_BPF_TIMEVAL" >&5
+$as_echo "$ac_cv_type_struct_BPF_TIMEVAL" >&6; }
+if test "x$ac_cv_type_struct_BPF_TIMEVAL" = x""yes; then
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_STRUCT_BPF_TIMEVAL 1
+_ACEOF
+
+
+fi
+
 	;;
 
 dag)
diff --git a/libpcap/configure.in b/libpcap/configure.in
index 7f67d8af9..b177e132d 100644
--- a/libpcap/configure.in
+++ b/libpcap/configure.in
@@ -381,6 +381,19 @@ bpf)
 		[define if the system supports zerocopy BPF])
 	    ],
 	    AC_MSG_RESULT(no))
+
+	    #
+	    # Check whether we have struct BPF_TIMEVAL.
+	    #
+	    AC_CHECK_TYPES(struct BPF_TIMEVAL,,,
+		[
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#ifdef HAVE_SYS_IOCCOM_H
+#include <sys/ioccom.h>
+#endif
+#include <net/bpf.h>
+		    ])
 	;;
 
 dag)
diff --git a/libpcap/pcap-bpf.c b/libpcap/pcap-bpf.c
index 6ec6515fb..ce3327f8f 100644
--- a/libpcap/pcap-bpf.c
+++ b/libpcap/pcap-bpf.c
@@ -1859,16 +1859,45 @@ pcap_activate_bpf(pcap_t *p)
 		 * XXX - is this seconds/nanoseconds in AIX?
 		 * (Treating it as such doesn't fix the timeout
 		 * problem described below.)
+		 *
+		 * XXX - Mac OS X 10.6 mishandles BIOCSRTIMEOUT in
+		 * 64-bit userland - it takes, as an argument, a
+		 * "struct BPF_TIMEVAL", which has 32-bit tv_sec
+		 * and tv_usec, rather than a "struct timeval".
+		 *
+		 * If this platform defines "struct BPF_TIMEVAL",
+		 * we check whether the structure size in BIOCSRTIMEOUT
+		 * is that of a "struct timeval" and, if not, we use
+		 * a "struct BPF_TIMEVAL" rather than a "struct timeval".
+		 * (That way, if the bug is fixed in a future release,
+		 * we will still do the right thing.)
 		 */
 		struct timeval to;
-		to.tv_sec = p->md.timeout / 1000;
-		to.tv_usec = (p->md.timeout * 1000) % 1000000;
-		if (ioctl(p->fd, BIOCSRTIMEOUT, (caddr_t)&to) < 0) {
-			snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "BIOCSRTIMEOUT: %s",
-			    pcap_strerror(errno));
-			status = PCAP_ERROR;
-			goto bad;
+#ifdef HAVE_STRUCT_BPF_TIMEVAL
+		struct BPF_TIMEVAL bpf_to;
+
+		if (IOCPARM_LEN(BIOCSRTIMEOUT) != sizeof(struct timeval)) {
+			bpf_to.tv_sec = p->md.timeout / 1000;
+			bpf_to.tv_usec = (p->md.timeout * 1000) % 1000000;
+			if (ioctl(p->fd, BIOCSRTIMEOUT, (caddr_t)&bpf_to) < 0) {
+				snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
+				    "BIOCSRTIMEOUT: %s", pcap_strerror(errno));
+				status = PCAP_ERROR;
+				goto bad;
+			}
+		} else {
+#endif
+			to.tv_sec = p->md.timeout / 1000;
+			to.tv_usec = (p->md.timeout * 1000) % 1000000;
+			if (ioctl(p->fd, BIOCSRTIMEOUT, (caddr_t)&to) < 0) {
+				snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
+				    "BIOCSRTIMEOUT: %s", pcap_strerror(errno));
+				status = PCAP_ERROR;
+				goto bad;
+			}
+#ifdef HAVE_STRUCT_BPF_TIMEVAL
 		}
+#endif
 	}
 
 #ifdef _AIX