diff --git a/src/blocks/affineDecrypt.js b/src/blocks/affineDecrypt.js
index 1d6fb89..06da530 100644
--- a/src/blocks/affineDecrypt.js
+++ b/src/blocks/affineDecrypt.js
@@ -45,7 +45,7 @@ module.exports =  {
     return text
     .split("")
     .map(require("./util/toNum.js"))
-    .map((num)=>(reverseLookupTable[num]))
+    .map((num)=>(Number.isInteger(num) ? reverseLookupTable[num] : num))
     .map(require("./util/toChar.js"))
     .join("");
   },
diff --git a/src/blocks/affineEncrypt.js b/src/blocks/affineEncrypt.js
index e9aaa79..e0dd38d 100644
--- a/src/blocks/affineEncrypt.js
+++ b/src/blocks/affineEncrypt.js
@@ -45,7 +45,7 @@ module.exports =  {
     return text
     .split("")
     .map(require("./util/toNum.js"))
-    .map((num)=>(lookupTable[num]))
+    .map((num)=>(Number.isInteger(num) ? lookupTable[num] : num))
     .map(require("./util/toChar.js"))
     .join("");
   },
diff --git a/src/blocks/substitution.js b/src/blocks/substitution.js
index 600e73c..500a2f6 100644
--- a/src/blocks/substitution.js
+++ b/src/blocks/substitution.js
@@ -18,7 +18,7 @@ module.exports =  {
   execute: function({text, mapping}, elem){
     mapping = mapping.toLowerCase();
     var letterMapping = {};
-    for(var i = 0; i < (mapping.length - 1); i++){
+    for(var i = 0; i < (mapping.length - 1); i = i + 2){
       letterMapping[mapping[i]] = mapping[i+1];
     }
 
@@ -26,15 +26,10 @@ module.exports =  {
     .split("")
     .map((char)=>{
       if(char.toLowerCase() in letterMapping){
-        if(char.toLowerCase() == char){
-          return letterMapping[char];
-        }
-        else{
-          return letterMapping[char.toLowerCase()].toUpperCase();
-        }
+        return letterMapping[char.toLowerCase()]
       }
       else{
-        return char;
+        return char.toLowerCase();
       }
     })
     .join("");