diff --git a/src/core/operations/ToCaseInsensitiveRegex.mjs b/src/core/operations/ToCaseInsensitiveRegex.mjs
index 28bd3dc9..4850846d 100644
--- a/src/core/operations/ToCaseInsensitiveRegex.mjs
+++ b/src/core/operations/ToCaseInsensitiveRegex.mjs
@@ -32,7 +32,56 @@ class ToCaseInsensitiveRegex extends Operation {
      * @returns {string}
      */
     run(input, args) {
-        return input.replace(/[a-z]/ig, m => `[${m.toLowerCase()}${m.toUpperCase()}]`);
+        /**
+         * Simulates look behind behaviour since javascript doesn't support it.
+         *
+         * @param {string} input
+         * @returns {string}
+         */
+        function preProcess(input) {
+            let result = "";
+            for (let i = 0; i < input.length; i++) {
+                const temp = input.charAt(i);
+                if (temp.match(/[a-zA-Z]/g) && (input.charAt(i-1) !== "-") && (input.charAt(i+1) !== "-"))
+                    result += "[" + temp.toLowerCase() + temp.toUpperCase() + "]";
+                else
+                    result += temp;
+            }
+            return result;
+        }
+
+        input = preProcess(input);
+
+        // Example: [a-z] -> [a-zA-Z]
+        input = input.replace(/[a-z]-[a-z]/g, m => `${m}${m[0].toUpperCase()}-${m[2].toUpperCase()}`);
+        
+        // Example: [a-z] -> [a-zA-Z]
+        input = input.replace(/[A-Z]-[A-Z]/g, m => `${m}${m[0].toLowerCase()}-${m[2].toLowerCase()}`);
+        
+        // Example: [H-d] -> [A-DH-dh-z]
+        input = input.replace(/[A-Z]-[a-z]/g, m => `A-${m[2].toUpperCase()}${m}${m[0].toLowerCase()}-z`);
+        
+        // Example: [!-D] -> [!-Da-d]
+        input = input.replace(/[ -@]-[A-Z]/g, m => `${m}a-${m[2].toLowerCase()}`);
+        
+        // Example: [%-^] -> [%-^a-z]
+        input = input.replace(/[ -@]-[[-`]/g, m => `${m}a-z`);
+        
+        // Example: [K-`] -> [K-`k-z]
+        input = input.replace(/[A-Z]-[[-`]/g, m => `${m}${m[0].toLowerCase()}-z`);
+        
+        // Example: [[-}] -> [[-}A-Z]
+        input = input.replace(/[[-`]-[{-~]/g, m => `${m}A-Z`);
+        
+        // Example: [b-}] -> [b-}B-Z]
+        input = input.replace(/[a-z]-[{-~]/g, m => `${m}${m[0].toUpperCase()}-Z`);
+        
+        // Example: [<-j] -> [<-z]
+        input = input.replace(/[ -@]-[a-z]/g, m => `${m[0]}-z`);
+        
+        // Example: [^-j] -> [A-J^-j]
+        input = input.replace(/[[-`]-[a-z]/g, m => `A-${m[2].toUpperCase()}${m}`);
+        return input;
     }
 }