diff --git a/src/core/lib/Base45.mjs b/src/core/lib/Base45.mjs
index d3e279fa..67fee471 100644
--- a/src/core/lib/Base45.mjs
+++ b/src/core/lib/Base45.mjs
@@ -24,4 +24,4 @@ export function highlightFromBase45(pos, args) {
     return pos;
 }
 
-export const ALPHABET = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ $%*+-./:";
+export const ALPHABET = "0-9A-Z $%*+\\-./:";
diff --git a/src/core/operations/FromBase45.mjs b/src/core/operations/FromBase45.mjs
index 890d35d6..2625d782 100644
--- a/src/core/operations/FromBase45.mjs
+++ b/src/core/operations/FromBase45.mjs
@@ -27,6 +27,13 @@ class FromBase45 extends Operation {
         this.infoURL = "https://wikipedia.org/wiki/List_of_numeral_systems";
         this.inputType = "string";
         this.outputType = "byteArray";
+        this.args = [
+            {
+                name: "Alphabet",
+                type: "string",
+                value: ALPHABET
+            }
+        ];
 
         this.highlight = highlightFromBase45;
         this.highlightReverse = highlightToBase45;
@@ -39,6 +46,7 @@ class FromBase45 extends Operation {
      */
     run(input, args) {
         if (!input) return [];
+        const alphabet = Utils.expandAlphRange(args[0]);
 
         const res = [];
 
@@ -46,7 +54,7 @@ class FromBase45 extends Operation {
             triple.reverse();
             let b = 0;
             for (const c of triple) {
-                const idx = ALPHABET.indexOf(c);
+                const idx = alphabet.indexOf(c);
                 if (idx === -1) {
                     throw new OperationError(`Character not in alphabet: '${c}'`);
                 }
diff --git a/src/core/operations/ToBase45.mjs b/src/core/operations/ToBase45.mjs
index d7455dca..40dd96de 100644
--- a/src/core/operations/ToBase45.mjs
+++ b/src/core/operations/ToBase45.mjs
@@ -29,7 +29,7 @@ class ToBase45 extends Operation {
             {
                 name: "Alphabet",
                 type: "string",
-                value: "0-9A-Za-z"
+                value: ALPHABET
             }
         ];
 
@@ -44,6 +44,7 @@ class ToBase45 extends Operation {
      */
     run(input, args) {
         input = new Uint8Array(input);
+        const alphabet = Utils.expandAlphRange(args[0]);
         if (!input) return "";
 
         const res = [];
@@ -57,7 +58,7 @@ class ToBase45 extends Operation {
 
             let chars = 0;
             do {
-                res.push(ALPHABET[b % 45]);
+                res.push(alphabet[b % 45]);
                 chars++;
                 b = Math.floor(b / 45);
             } while (b > 0);
diff --git a/tests/operations/tests/Base45.mjs b/tests/operations/tests/Base45.mjs
index 1e821c6d..d1c17ea3 100644
--- a/tests/operations/tests/Base45.mjs
+++ b/tests/operations/tests/Base45.mjs
@@ -9,6 +9,8 @@
 
 import TestRegister from "../../lib/TestRegister.mjs";
 
+const defaultB45Alph = "0-9A-Z $%*+\\-./:";
+
 TestRegister.addTests([
     {
         name: "To Base45: nothing",
@@ -17,7 +19,7 @@ TestRegister.addTests([
         recipeConfig: [
             {
                 op: "To Base45",
-                args: [],
+                args: [defaultB45Alph],
             },
         ],
     },
@@ -28,7 +30,7 @@ TestRegister.addTests([
         recipeConfig: [
             {
                 op: "To Base45",
-                args: [],
+                args: [defaultB45Alph],
             },
         ],
     },
@@ -39,7 +41,7 @@ TestRegister.addTests([
         recipeConfig: [
             {
                 op: "To Base45",
-                args: [],
+                args: [defaultB45Alph],
             },
         ],
     },
@@ -50,7 +52,7 @@ TestRegister.addTests([
         recipeConfig: [
             {
                 op: "To Base45",
-                args: [],
+                args: [defaultB45Alph],
             },
         ],
     },
@@ -61,7 +63,7 @@ TestRegister.addTests([
         recipeConfig: [
             {
                 op: "From Base45",
-                args: [],
+                args: [defaultB45Alph],
             },
         ],
     },
@@ -72,7 +74,7 @@ TestRegister.addTests([
         recipeConfig: [
             {
                 op: "From Base45",
-                args: [],
+                args: [defaultB45Alph],
             },
         ],
     },
@@ -83,7 +85,7 @@ TestRegister.addTests([
         recipeConfig: [
             {
                 op: "From Base45",
-                args: [],
+                args: [defaultB45Alph],
             },
         ],
     },
@@ -94,7 +96,7 @@ TestRegister.addTests([
         recipeConfig: [
             {
                 op: "From Base45",
-                args: [],
+                args: [defaultB45Alph],
             },
         ],
     },