diff --git a/unix/ux_x11.c b/unix/ux_x11.c
index 91c95bbc..4df66d15 100644
--- a/unix/ux_x11.c
+++ b/unix/ux_x11.c
@@ -159,6 +159,11 @@ int platform_make_x11_server(Plug *plug, const char *progname, int mindisp,
                  * we expect read() to return EOF as soon as
                  * that process terminates.
                  */
+
+                close(0);
+                close(1);
+                close(2);
+
                 setpgid(0, 0);
                 close(cleanup_pipe[1]);
                 close(authfd);
diff --git a/unix/uxagentsock.c b/unix/uxagentsock.c
index 90e701ff..3fbbb84f 100644
--- a/unix/uxagentsock.c
+++ b/unix/uxagentsock.c
@@ -62,6 +62,11 @@ Socket *platform_make_agent_socket(
                  * we expect read() to return EOF as soon as
                  * that process terminates.
                  */
+
+                close(0);
+                close(1);
+                close(2);
+
                 setpgid(0, 0);
                 close(cleanup_pipe[1]);
                 while (read(cleanup_pipe[0], buf, sizeof(buf)) > 0);