diff --git a/awk/atbash-cipher/atbash-cipher.awk b/awk/atbash-cipher/atbash-cipher.awk
index e422723f..a08887e4 100644
--- a/awk/atbash-cipher/atbash-cipher.awk
+++ b/awk/atbash-cipher/atbash-cipher.awk
@@ -34,26 +34,20 @@ function atbash_cipher(input) {
         return "error: plain-text can't be empty"
     }
 
-    spacer = "" # is this needed here?
-
     for (i = 1; i <= length(filtered); i++) {
         letter = tolower(letters[i])
         #print "plain   letter: [" letter "]"
         shifted_letter = shift_letter(letter)
         #print "shifted letter: [" shifted_letter "]"
 
-        if (direction == "encode") {
-            if ((i - 1) % 5 == 0) {
-                spacer = " "
-            } else {
-                spacer = ""
-            }
-        }
-
         if (length(cipher_text) == 0) {
             cipher_text = shifted_letter
         } else {
-            cipher_text = cipher_text spacer shifted_letter
+            cipher_text = cipher_text shifted_letter
+        }
+
+        if (direction == "encode") {
+            cipher_text = gensub(/[a-z0-9]{5}\B/, "& ", "g", cipher_text)
         }
     }
 
diff --git a/awk/atbash-cipher/run-tests-awk.txt b/awk/atbash-cipher/run-tests-awk.txt
index 87580136..c343603a 100644
--- a/awk/atbash-cipher/run-tests-awk.txt
+++ b/awk/atbash-cipher/run-tests-awk.txt
@@ -25,6 +25,7 @@ awkunit.so
 
 gawk --lint --file=./atbash-cipher.awk < /dev/null > /dev/null
 gawk: ./atbash-cipher.awk:3: warning: `load' is a gawk extension
+gawk: ./atbash-cipher.awk:50: warning: `gensub' is a gawk extension
 
 real	0m0.005s
 user	0m0.002s
@@ -37,16 +38,16 @@ gawk: warning: function `assert' defined but never called directly
 gawk: ./awkunit.awk:26: warning: reference to uninitialized variable `_assert_exit'
 
 real	0m0.006s
-user	0m0.003s
-sys	0m0.002s
+user	0m0.002s
+sys	0m0.004s
 
 gawk --lint --file=./test-cases.awk < /dev/null > /dev/null
 gawk: ./test-cases.awk:8: warning: subscript of array `encode_cases' is null string
 gawk: ./test-cases.awk:22: warning: subscript of array `decode_cases' is null string
 
-real	0m0.004s
-user	0m0.002s
-sys	0m0.002s
+real	0m0.005s
+user	0m0.001s
+sys	0m0.003s
 
 exit 0
 
@@ -69,9 +70,9 @@ ok 12 decode all the letters
 ok 13 decode with too many spaces
 ok 14 decode with no spaces
 
-real	0m0.479s
-user	0m0.319s
-sys	0m0.187s
+real	0m0.597s
+user	0m0.394s
+sys	0m0.231s
 
 exit 0
 
@@ -238,9 +239,9 @@ Test 26:
 
 26 out of 26 tests passed!
 
-real	0m0.009s
+real	0m0.008s
 user	0m0.003s
-sys	0m0.006s
+sys	0m0.005s
 
 Tests Passed!
 
@@ -250,9 +251,9 @@ exit 0
 
 Running: misspell .
 
-real	0m0.033s
+real	0m0.042s
 user	0m0.041s
-sys	0m0.009s
+sys	0m0.022s
 
 ===============================================================================