diff --git a/ncat/scripts/conditional.lua b/ncat/scripts/conditional.lua
index 8af297542..aeb492068 100644
--- a/ncat/scripts/conditional.lua
+++ b/ncat/scripts/conditional.lua
@@ -2,6 +2,25 @@
 --input and makes a decision according to what the user entered. All happens
 --in an infinite loop.
 
+--This function reads a line of at most 8096 bytes (or whatever the first
+--parameter says) from standard input. Returns the string and a boolean value
+--that is true if we hit the newline (defined as "\r" or "\n") or false if the
+--line had to be truncated. This is here because io.stdin:read("*line") could
+--read to memory exhaustion if we received gigabytes of characters with no
+--newline.
+function read_line(max_len)
+    local ret = ""
+    for i = 1, (max_len or 8096) do
+        local chr = io.read(1)
+        if chr == "\r" or chr == "\n" then
+            return ret, true
+        end
+        ret = ret .. chr
+    end
+
+    return ret, false
+end
+
 while true do
 
   print "Here's a menu for you: "
@@ -10,7 +29,7 @@ while true do
 
   io.write "Please enter your choice: "
   io.flush(io.stdout)
-  i = io.read()
+  i = read_line()
 
   --WARNING! Without this line, the script will go into an infinite loop
   --that keeps consuming system resources when the connection gets broken.