diff --git a/src/cli.c b/src/cli.c
index 739107d..ce8635f 100644
--- a/src/cli.c
+++ b/src/cli.c
@@ -847,10 +847,14 @@
 		void *ctx = NULL;
 		uint32_t conn_flags = 0;
 
+		thread_isolate();
+
 		fdt = fdtab[fd];
 
-		if (!fdt.owner)
+		if (!fdt.owner) {
+			thread_release();
 			goto skip; // closed
+		}
 
 		if (fdt.iocb == conn_fd_handler) {
 			conn_flags = ((struct connection *)fdt.owner)->flags;
@@ -916,6 +920,8 @@
 			              li->bind_conf->frontend->id);
 		}
 
+		thread_release();
+
 		chunk_appendf(&trash, "\n");
 
 		if (ci_putchk(si_ic(si), &trash) == -1) {