diff --git a/release/tools/ec2.conf b/release/tools/ec2.conf
index be7891b59855..5f0e868a80eb 100644
--- a/release/tools/ec2.conf
+++ b/release/tools/ec2.conf
@@ -77,6 +77,12 @@ vm_extra_pre_umount() {
 	# by default for now.
 	echo 'hw.xbd.xbd_enable_indirect="0"' >> ${DESTDIR}/boot/loader.conf
 
+	# Some EC2 instances run on a version of Xen which has a bug relating
+	# to the migration of MSI-X interrupts; this is visible as SR-IOV
+	# networking (aka. "EC2 Enhanced Networking") not being able to pass
+	# packets.  Disable MSI-X interrupt migration to work around this bug.
+	echo 'machdep.disable_msix_migration="1"' >> ${DESTDIR}/boot/loader.conf
+
 	# The first time the AMI boots, the installed "first boot" scripts
 	# should be allowed to run:
 	# * ec2_configinit (download and process EC2 user-data)