diff --git a/src/format-cnpj/format-cnpj.test.ts b/src/format-cnpj/format-cnpj.test.ts
index ab15077..faf9902 100644
--- a/src/format-cnpj/format-cnpj.test.ts
+++ b/src/format-cnpj/format-cnpj.test.ts
@@ -116,4 +116,16 @@ describe("formatCnpj", () => {
 			"46.ABC.843/4850-00",
 		);
 	});
+
+	it("should allow all alphabet letters for version 2 (including E, O, T, U)", () => {
+		expect(formatCnpj("12ABC34501DE35", { version: 2 })).toBe(
+			"12.ABC.345/01DE-35",
+		);
+		expect(formatCnpj("12.ABC.345/01DE-35", { version: 2 })).toBe(
+			"12.ABC.345/01DE-35",
+		);
+		expect(formatCnpj("12OUT345000199", { version: 2 })).toBe(
+			"12.OUT.345/0001-99",
+		);
+	});
 });
diff --git a/src/format-cnpj/format-cnpj.ts b/src/format-cnpj/format-cnpj.ts
index 270bafe..d69f356 100644
--- a/src/format-cnpj/format-cnpj.ts
+++ b/src/format-cnpj/format-cnpj.ts
@@ -8,18 +8,8 @@ const sanitize = (
 	version?: FormatCnpjOptions["version"],
 ) => {
 	if (version === 2) {
-		const allowedChars = "0123456789ABCDFGHIJKLMNPQRSVWXYZ";
 		const enhancedValue = value.toString();
-
-		let result = "";
-
-		for (let i = 0; i < enhancedValue.length; i++) {
-			if (allowedChars.includes(enhancedValue[i].toUpperCase())) {
-				result += enhancedValue[i].toUpperCase();
-			}
-		}
-
-		return result;
+		return enhancedValue.replace(/[^A-Za-z0-9]/g, "").toUpperCase();
 	}
 
 	return sanitizeToDigits(value);