diff --git a/tools/wktcat.s b/tools/wktcat.s
index 92c7c56..21236fc 100644
--- a/tools/wktcat.s
+++ b/tools/wktcat.s
@@ -9,9 +9,6 @@
 "
 " ./a7out a.out z1 z1
 " <the text you typed in will be displayed twice>
-"
-" Also, the current coding is hideous and needs refactoring.
-" I'm still coming to grips with PDP-7 assembly code.
 
 main:
    " Load the pointer pointer in 017777 to see if we have any arguments
@@ -19,23 +16,24 @@ main:
    sad d4		" Skip if we have more than four argument words
      jmp stdinout	" Only four argument words, so no arguments
 
-   lac 017777
-   tad d1		" Bump AC up by 5 so that it points at the first argument
+   lac 017777           " Move five words past the argument word count
+   tad d1               " so that AC points at the first argument
    tad d4
 
-" This section opens files, and copies their contents to standard output
+" This section opens files and copies their contents to standard output
 catfiles:
-   " We start with AC pointing to an argument. Save it at label 1f
+   " We start with AC pointing to an argument. Save it at the "name" label
    dac name
 
    " Open the file and get the fd into AC
    sys open; name:0; 0; 0
    spa
-     jmp badfile	" Bad fd, exit with an error message
+     jmp badfile	" Negative fd, exit with an error message
    dac fd		" Save the file descriptor
 
 fileloop:
    " Read five words into the buffer from the input file
+   " Five was chosen arbitrarily
    lac fd
    sys read; buf; 5
    spa			" Skip if result was >= 0
@@ -76,26 +74,15 @@ end:
    sys exit
 
 " This section copies from standard input to standard output
+" We cheat by setting the fd value to zero and storing 8
+" into the argc word count, so that when the code hits
+" fileend, the word count drops to 4 and we exit.
 stdinout:
-   " Read five words into the buffer from stdin
-   " Five was chosen arbitrarily
+   lac d8
+   dac 017777 i		" Save 8 into the word count
    lac d0
-   sys read; buf; 5
-   spa			" Skip if result was >= 0
-     jmp error		" Result was -ve, so error result
-   sna			" Skip if result was >0
-     jmp end		" Result was zero, so nothing left to read
-
-   " Save the count of words read in
-   dac 1f
-
-   " Write five words from the buffer to stdout
-   lac d1
-   sys write; buf; 1:0
-
-   " and loop back for more words to read
-   jmp stdinout
-
+   dac fd		" Save file descriptor 0
+   jmp fileloop
 
 " This code comes from the real cat.s
 badfile:
@@ -107,12 +94,11 @@ badfile:
    sys write; 1f; 2
    sys exit		" and exit
 
-1: 040; 077012
-
+1: 040; 077012		" String literal: " ?\n"
 
 error:
-   " Print an "err read" string and exit
-   lac d1
+   " Print an "err read" string on stderr and exit
+   lac d8
    sys write; noreadstr; 5
    sys exit
 
@@ -120,11 +106,11 @@ noreadstr:
    <er>;<r 040;<re>;<ad>;012000
 
 fd: 0		" fd of the open file
-d0: 0		" Constants 0 and 1
+d0: 0		" Constants 0, 1, 4 and 8
 d1: 1
 d4: 4
 d8: 8		" stderr seems to have fd 8
-minus4:	0777774	" -4 constant
+minus4:	0777774	" Constant -4
 
 " Input buffer for read
 buf: 0; 0; 0; 0; 0