diff --git a/tests/sys/fs/fusefs/mockfs.hh b/tests/sys/fs/fusefs/mockfs.hh
--- a/tests/sys/fs/fusefs/mockfs.hh
+++ b/tests/sys/fs/fusefs/mockfs.hh
@@ -284,7 +284,7 @@
 	pthread_t m_daemon_id;
 
 	/* file descriptor of /dev/fuse control device */
-	int m_fuse_fd;
+	volatile int m_fuse_fd;
 	
 	/* The minor version of the kernel API that this mock daemon targets */
 	uint32_t m_kernel_minor_version;
diff --git a/tests/sys/fs/fusefs/mockfs.cc b/tests/sys/fs/fusefs/mockfs.cc
--- a/tests/sys/fs/fusefs/mockfs.cc
+++ b/tests/sys/fs/fusefs/mockfs.cc
@@ -870,6 +870,7 @@
 	struct timeval timeout_tv;
 	const int timeout_ms = 999;
 	int timeout_int, nfds;
+	int fuse_fd;
 
 	switch (m_pm) {
 	case BLOCKING:
@@ -906,19 +907,22 @@
 		ASSERT_TRUE(fds[0].revents & POLLIN);
 		break;
 	case SELECT:
+		fuse_fd = m_fuse_fd;
+		if (fuse_fd < 0)
+			break;
 		timeout_tv.tv_sec = 0;
 		timeout_tv.tv_usec = timeout_ms * 1'000;
-		nfds = m_fuse_fd + 1;
+		nfds = fuse_fd + 1;
 		while (nready == 0) {
 			FD_ZERO(&readfds);
-			FD_SET(m_fuse_fd, &readfds);
+			FD_SET(fuse_fd, &readfds);
 			nready = select(nfds, &readfds, NULL, NULL,
 				&timeout_tv);
 			if (m_quit)
 				return;
 		}
 		ASSERT_LE(0, nready) << strerror(errno);
-		ASSERT_TRUE(FD_ISSET(m_fuse_fd, &readfds));
+		ASSERT_TRUE(FD_ISSET(fuse_fd, &readfds));
 		break;
 	default:
 		FAIL() << "not yet implemented";