diff --git a/atlas_os/CMC.lua b/atlas_os/CMC.lua
index aaac0e6..b5c9f0e 100644
--- a/atlas_os/CMC.lua
+++ b/atlas_os/CMC.lua
@@ -108,13 +108,22 @@ reg("ls", function(a)
   local opts = {}
   for i = 1, #a do
     if a[i]:sub(1, 1) == "-" then
-      opts[a[i]] = true
+      local opt = a[i]
+      for j = 2, #opt do
+        local c = opt:sub(j, j)
+        if c ~= "a" and c ~= "l" then
+          error("ls: unknown option '" .. opt .. "'")
+        end
+      end
+      opts[opt] = true
     else
       path = resolvePath(a[i])
     end
   end
   local cmdStr = "ls"
-  if #a > 0 then cmdStr = "ls " .. table.concat(a, " ") end
+  for i = 1, #a do
+    cmdStr = cmdStr .. " " .. tostring(a[i])
+  end
   pendingCmd = { name = "ls", opts = opts, path = path,
                  prompt = curUser .. " " .. cwd .. "> " .. cmdStr }
   state = ST_WAIT_FS
@@ -254,6 +263,7 @@ local function handleFSResponse(op, data)
   end
 
   queueLines(lines)
+  out[4] = ""
   pendingCmd = nil
   state = ST_IDLE
 end
diff --git a/atlas_os/MMC.lua b/atlas_os/MMC.lua
index ba430e3..b88d018 100644
--- a/atlas_os/MMC.lua
+++ b/atlas_os/MMC.lua
@@ -267,11 +267,15 @@ function upd()
 
   if inp[1] ~= nil then
     local req = tostring(inp[1])
-    if #req > 0 and req ~= prevReq then
+    if #req == 0 then
+      prevReq = ""
+    elseif req ~= prevReq then
       prevReq = req
       local resp = processReq(req)
       out[1] = resp
     end
+  else
+    prevReq = ""
   end
 
   table.clear(inp)