1 files changed, 7 insertions, 0 deletions
diff --git a/src/ninep/ctl.zig b/src/ninep/ctl.zig
index 11de3c1c..325fc8c8 100644
--- a/src/ninep/ctl.zig
+++ b/src/ninep/ctl.zig
@@ -138,7 +138,14 @@ pub fn command(p: *Pardes, req: Req, serial: ?u32, exec: bool) Reply {
             if (!apply) continue;
             const id = if (serial) |s| p.paneBySerial(s) orelse break else p.active;
             if (p.panes[id] == null) return Reply.fail(req.tag, E.NOENT);
+            p.fs.no_pane_slot = false;
             run(p, id, exec, text);
+            // A pane it would have opened had no slot: the write fails, and
+            // a look reads back nothing.
+            if (p.fs.no_pane_slot) {
+                p.fs.results_len = 0;
+                return tree.failText(req.tag, E.IO, p.fs.ename[0..p.fs.no_pane_slot_len]);
+            }
         }
     }
     return .{ .tag = req.tag, .written = @intCast(req.data.len) };