diff --git a/sys/apps/genotp.lua b/sys/apps/genotp.lua
index cdaf6eb..e6bd5a1 100644
--- a/sys/apps/genotp.lua
+++ b/sys/apps/genotp.lua
@@ -1,14 +1,22 @@
 local SHA = require("opus.crypto.sha2")
 
-local acceptableCharacters = {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"}
+local acceptableCharacters = {}
+for c = 0, 127 do
+  local char = string.char(c)
+  -- exclude potentially ambiguous characters
+  if char:match("[1-9a-zA-Z]") and char:match("[^OIl]") end
+    table.insert(acceptableCharacters, char)
+  end
+end
 local acceptableCharactersLen = #acceptableCharacters
-   
 local password = ""
 
-for _i = 1, 8 do
+for i = 1, 10 do
     password = password .. acceptableCharacters[math.random(acceptableCharactersLen)]
 end
 
 os.queueEvent("set_otp", SHA.compute(password))
 
-print("Your one-time password is: " .. password)
\ No newline at end of file
+print("This allows one other device to permanently gain access to this device.")
+print("Use the trust settings in System to revert this.")
+print("Your one-time password is: " .. password)