diff --git a/src/core/operations/FromBase32.mjs b/src/core/operations/FromBase32.mjs
index 06674919f..20944cca6 100644
--- a/src/core/operations/FromBase32.mjs
+++ b/src/core/operations/FromBase32.mjs
@@ -5,6 +5,7 @@
  */
 
 import Operation from "../Operation.mjs";
+import OperationError from "../errors/OperationError.mjs";
 import Utils from "../Utils.mjs";
 import {ALPHABET_OPTIONS} from "../lib/Base32.mjs";
 
@@ -65,11 +66,14 @@ class FromBase32 extends Operation {
     run(input, args) {
         if (!input) return [];
 
-        const alphabet = args[0] ?
-                Utils.expandAlphRange(args[0]).join("") : "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567=",
+        const alphabet = Utils.expandAlphRange(args[0]).join(""),
             removeNonAlphChars = args[1],
             output = [];
 
+        if (alphabet.length !== 33) {
+            throw new OperationError("Alphabet must be of length 33"); // 32 characters + 1 padding
+        }
+
         let chr1, chr2, chr3, chr4, chr5,
             enc1, enc2, enc3, enc4, enc5, enc6, enc7, enc8,
             i = 0;
diff --git a/src/core/operations/ToBase32.mjs b/src/core/operations/ToBase32.mjs
index 44eb8b484..9e7255c2a 100644
--- a/src/core/operations/ToBase32.mjs
+++ b/src/core/operations/ToBase32.mjs
@@ -7,6 +7,7 @@
 import Operation from "../Operation.mjs";
 import Utils from "../Utils.mjs";
 import {ALPHABET_OPTIONS} from "../lib/Base32.mjs";
+import OperationError from "../errors/OperationError.mjs";
 
 /**
  * To Base32 operation
@@ -43,7 +44,11 @@ class ToBase32 extends Operation {
         if (!input) return "";
         input = new Uint8Array(input);
 
-        const alphabet = args[0] ? Utils.expandAlphRange(args[0]).join("") : "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567=";
+        const alphabet = Utils.expandAlphRange(args[0]).join("");
+        if (alphabet.length !== 33) {
+            throw new OperationError("Alphabet must be of length 33"); // 32 characters + 1 padding
+        }
+
         let output = "",
             chr1, chr2, chr3, chr4, chr5,
             enc1, enc2, enc3, enc4, enc5, enc6, enc7, enc8,
diff --git a/tests/operations/tests/Base32.mjs b/tests/operations/tests/Base32.mjs
index 28913b855..0afb3787f 100644
--- a/tests/operations/tests/Base32.mjs
+++ b/tests/operations/tests/Base32.mjs
@@ -44,6 +44,8 @@ const ALL_BYTES_EXTENDED_OUT = "000G40O40K30E209185GO38E1S8124GJ2GAHC5OO34D1M70T
 const ALL_BYTES_STANDARD_OUT = "AAAQEAYEAUDAOCAJBIFQYDIOB4IBCEQTCQKRMFYYDENBWHA5DYPSAIJCEMSCKJRHFAUSUKZMFUXC6MBRGIZTINJWG44DSOR3HQ6T4P2AIFBEGRCFIZDUQSKKJNGE2TSPKBIVEU2UKVLFOWCZLJNVYXK6L5QGCYTDMRSWMZ3INFVGW3DNNZXXA4LSON2HK5TXPB4XU634PV7H7AEBQKBYJBMGQ6EITCULRSGY5D4QSGJJHFEVS2LZRGM2TOOJ3HU7UCQ2FI5EUWTKPKFJVKV2ZLNOV6YLDMVTWS23NN5YXG5LXPF5X274BQOCYPCMLRWHZDE4VS6MZXHM7UGR2LJ5JVOW27MNTWW33TO55X7A4HROHZHF43T6R2PK5PWO33XP6DY7F47U6X3PP6HZ7L57Z7P674======";
 const ALL_BYTES_CROCKFORD_OUT = "000G40R40M30E209185GR38E1W8124GK2GAHC5RR34D1P70X3RFJ08924CJ2A9H750MJMASC5MQ2YC1H68SK8D9P6WW3JEHV7GYKWFT085146H258S3MGJAA9D64TKJFA18N4MTMANB5EP2SB9DNRQAYBXG62RK3CHJPCSV8D5N6PV3DDSQQ0WBJEDT7AXKQF1WQMYVWFNZ7Z041GA1R91C6GY48K2MBHJ6RX3WGJ699754NJTBSH6CTKEE9V7MZM2GT58X4MPKAFA59NANTSBDENYRB3CNKPJTVDDXRQ6XBQF5XQTZW1GE2RF2CBHP7S34WNJYCSQ7CZM6HTB9X9NEPTZCDKPPVVKEXXQZ0W7HE7S75WVKYHTFAXFPEVVQFY3RZ5WZMYQVFFY7SZBXZSZFYZW======";
 
+const WRONG_ALPHABET = "Alphabet must be of length 33"
+
 TestRegister.addTests([
     {
         name: "To Base32 Standard: nothing",
@@ -243,5 +245,71 @@ TestRegister.addTests([
             },
         ],
     },
+    {
+        name: "To Base32 Standard: wrong alphabet",
+        input: STANDARD_INP,
+        expectedOutput: WRONG_ALPHABET,
+        recipeConfig: [
+            {
+                op: "To Base32",
+                args: [""],
+            },
+        ],
+    },
+    {
+        name: "To Base32 Hex Extended: wrong alphabet",
+        input: EXTENDED_INP,
+        expectedOutput: WRONG_ALPHABET,
+        recipeConfig: [
+            {
+                op: "To Base32",
+                args: [""],
+            },
+        ],
+    },
+    {
+        name: "To Base32 Crockford: wrong alphabet",
+        input: CROCKFORD_INP,
+        expectedOutput: WRONG_ALPHABET,
+        recipeConfig: [
+            {
+                op: "To Base32",
+                args: [""],
+            },
+        ],
+    },
+    {
+        name: "From Base32 Standard: wrong alphabet",
+        input: STANDARD_OUT,
+        expectedOutput: WRONG_ALPHABET,
+        recipeConfig: [
+            {
+                op: "From Base32",
+                args: ["", false],
+            },
+        ],
+    },
+    {
+        name: "From Base32 Hex Extended: wrong alphabet",
+        input: EXTENDED_OUT,
+        expectedOutput: WRONG_ALPHABET,
+        recipeConfig: [
+            {
+                op: "From Base32",
+                args: ["", false],
+            },
+        ],
+    },
+    {
+        name: "From Base32 Crockford: wrong alphabet",
+        input: CROCKFORD_OUT,
+        expectedOutput: WRONG_ALPHABET,
+        recipeConfig: [
+            {
+                op: "From Base32",
+                args: ["", false],
+            },
+        ],
+    },
 ]);