diff --git a/server/auth.ts b/server/auth.ts
index 590fd9a..11665e4 100644
--- a/server/auth.ts
+++ b/server/auth.ts
@@ -1,5 +1,11 @@
 import { authErrorData } from "./error_data.ts";
-import { getJwtFromBearer, isArray, isPresent, type Payload } from "./deps.ts";
+import {
+  getJwtFromBearer,
+  isArray,
+  isFunction,
+  isPresent,
+  type Payload,
+} from "./deps.ts";
 import { type CreationInput } from "./creation.ts";
 import { type AuthInput } from "./response.ts";
 import { type ValidationSuccess } from "./validation.ts";
@@ -49,7 +55,7 @@ function processAuthData(
     ) {
       try {
         const verify = authData.verification;
-        if (typeof verify === "function") {
+        if (isFunction(verify)) {
           const jwt = getJwtFromBearer(authData.headers);
           const payload = await verify(jwt, authData.options);
           return { validationObject, methods, options, payload };
diff --git a/server/deps.ts b/server/deps.ts
index a9808b0..a70c76f 100644
--- a/server/deps.ts
+++ b/server/deps.ts
@@ -10,6 +10,9 @@ export {
 } from "https://dev.zaubrik.com/portal@v0.2.7/functions/mod.ts";
 export {
   isArray,
+  isFunction,
+  isNotNull,
   isObject,
   isPresent,
+  isString,
 } from "https://dev.zaubrik.com/sorcery@v0.1.5/type.js";
diff --git a/server/object.js b/server/object.js
deleted file mode 100644
index 8113fe3..0000000
--- a/server/object.js
+++ /dev/null
@@ -1,11 +0,0 @@
-/**
- * isObject.
- * @param {unknown} input
- * @returns {input is Record<string, any>}
- */
-export function isObject(input) {
-  return (
-    input !== null && typeof input === "object" &&
-    Array.isArray(input) === false
-  );
-}
diff --git a/server/response.ts b/server/response.ts
index e2fe219..f7bfa3b 100644
--- a/server/response.ts
+++ b/server/response.ts
@@ -1,11 +1,12 @@
-import { createRpcResponseOrBatch } from "./creation.ts";
-import { validateRequest } from "./validation.ts";
-import { type JsonValue } from "../rpc_types.ts";
 import {
   type CryptoKeyOrUpdateInput,
+  isFunction,
   verifyJwt,
   type VerifyOptions,
 } from "./deps.ts";
+import { createRpcResponseOrBatch } from "./creation.ts";
+import { validateRequest } from "./validation.ts";
+import { type JsonValue } from "../rpc_types.ts";
 
 export type Methods = {
   // deno-lint-ignore no-explicit-any
@@ -32,7 +33,7 @@ export function ensureVerify(authInput: AuthInput): AuthInput {
   const verification = authInput.verification;
   return {
     ...authInput,
-    verification: typeof verification === "function"
+    verification: isFunction(verification)
       ? verification
       : verifyJwt(verification),
   };
diff --git a/server/validation.ts b/server/validation.ts
index 8dbafc5..e405885 100644
--- a/server/validation.ts
+++ b/server/validation.ts
@@ -1,4 +1,4 @@
-import { isObject } from "./deps.ts";
+import { isFunction, isNotNull, isObject, isString } from "./deps.ts";
 import {
   invalidParamsErrorData,
   invalidRequestErrorData,
@@ -36,7 +36,7 @@ function isRpcVersion(input: unknown): input is "2.0" {
 }
 
 function isRpcMethod(input: unknown): input is string {
-  return typeof input === "string" && !input.startsWith("rpc.");
+  return isString(input) && !input.startsWith("rpc.");
 }
 
 export function isRpcParams(input: unknown): input is JsonArray | JsonObject {
@@ -98,7 +98,7 @@ export function validateRpcRequestObject(
         id: isRpcId(decodedBody.id) ? decodedBody.id : null,
         isError: true,
       };
-    } else if (typeof methods[decodedBody.method] !== "function") {
+    } else if (!(isFunction(methods[decodedBody.method]))) {
       return {
         id: decodedBody.id,
         isError: true,
diff --git a/test_deps.ts b/test_deps.ts
index ebcc1e7..dbc5c03 100644
--- a/test_deps.ts
+++ b/test_deps.ts
@@ -2,5 +2,5 @@ export {
   assertEquals,
   assertNotEquals,
   assertThrows,
-} from "https://deno.land/std@0.223.0/testing/asserts.ts";
+} from "https://deno.land/std@0.224.0/testing/asserts.ts";
 export { create, type Payload } from "https://deno.land/x/djwt@v3.0.2/mod.ts";