diff --git a/src/config.ts b/src/config.ts
index 8c24f67..a98c98d 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -1,7 +1,8 @@
 import { Condition } from './condition';
+import { CookiePersister } from './cookiePersister';
 import { removeAbTestParameter } from './query';
 import { ConsoleTracking, Tracking } from './tracking';
-import { CookiePersister, UserSessionPersister } from './userSessionPersister';
+import { UserSessionPersister } from './userSessionPersister';
 
 export interface Config {
     cookieName: string;
diff --git a/src/cookiePersister.ts b/src/cookiePersister.ts
new file mode 100644
index 0000000..8ff6587
--- /dev/null
+++ b/src/cookiePersister.ts
@@ -0,0 +1,33 @@
+import config from './config';
+import { UserSessionPersister } from './userSessionPersister';
+
+export class CookiePersister implements UserSessionPersister {
+  private static createCookie(name: string, value: string, days: number): void {
+      let expires = '';
+      if (days) {
+          const date = new Date();
+          date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
+          expires = '; expires=' + date.toUTCString();
+      }
+      document.cookie = name + '=' + value + expires + '; path=/';
+  }
+  private static readCookie(name: string): string | null {
+      const nameEq = name + '=';
+      const ca = document.cookie.split(';');
+      for (let c of ca) {
+          while (c.charAt(0) === ' ') {
+              c = c.substring(1, c.length);
+          }
+          if (c.indexOf(nameEq) === 0) {
+              return c.substring(nameEq.length, c.length);
+          }
+      }
+      return null;
+  }
+  public loadUserSession() {
+      return CookiePersister.readCookie(config.cookieName);
+  }
+  public saveUserSession(userSession: string, daysToLive: number) {
+      CookiePersister.createCookie(config.cookieName, userSession, daysToLive);
+  }
+}
diff --git a/src/inMemoryPersister.ts b/src/inMemoryPersister.ts
new file mode 100644
index 0000000..b0a388d
--- /dev/null
+++ b/src/inMemoryPersister.ts
@@ -0,0 +1,13 @@
+import { UserSessionPersister } from './userSessionPersister';
+
+export class InMemoryPersister implements UserSessionPersister {
+  private endOfLife: number = 0;
+  private storage: string = '';
+  public loadUserSession() {
+      return !this.endOfLife || (Date.now() > this.endOfLife) ? '' : this.storage;
+  }
+  public saveUserSession(userSession: string, daysToLive: number) {
+      this.storage = userSession;
+      this.endOfLife = Date.now() + (daysToLive * 24 * 60 * 60 * 1000);
+  }
+}
diff --git a/src/index.ts b/src/index.ts
index 0e8ceac..5f36f41 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,3 +1,5 @@
+import { CookiePersister } from './cookiePersister';
+import { InMemoryPersister } from './inMemoryPersister';
 import {
     config,
     create,
@@ -12,7 +14,7 @@ import {
 } from './main';
 import { SplitTest } from './splitTest';
 import { uiFactory } from './ui';
-import { UserSessionPersister, InMemoryPersister, CookiePersister } from './userSessionPersister';
+import { UserSessionPersister } from './userSessionPersister';
 
 const ui = uiFactory(
     testsObservable,
diff --git a/src/main.ts b/src/main.ts
index 0c44bd0..aeec0c6 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -31,9 +31,9 @@ export function config(userConfig: Partial<Config> = {}) {
         _config.onVariationChange = userConfig.onVariationChange;
     }
     if (userConfig.sessionPersister) {
-        const userSession = _config.sessionPersister.loadUserSession() || '';
+        const session = _config.sessionPersister.loadUserSession() || '';
         _config.sessionPersister = userConfig.sessionPersister;
-        _config.sessionPersister.saveUserSession(userSession, _config.userSessionDaysToLive);
+        _config.sessionPersister.saveUserSession(session, _config.userSessionDaysToLive);
     }
 }
 
diff --git a/src/userSessionPersister.ts b/src/userSessionPersister.ts
index 679503a..bbdf19b 100644
--- a/src/userSessionPersister.ts
+++ b/src/userSessionPersister.ts
@@ -3,44 +3,3 @@ export interface UserSessionPersister {
     loadUserSession(): string | null;
     saveUserSession(userSession: string, daysToLive: number): void;
 }
-export class CookiePersister implements UserSessionPersister {
-    public loadUserSession() {
-        return CookiePersister.readCookie(config.cookieName);
-    }
-    public saveUserSession(userSession: string, daysToLive: number) {
-        CookiePersister.createCookie(config.cookieName, userSession, daysToLive);
-    }
-    private static createCookie(name: string, value: string, days: number): void {
-        let expires = '';
-        if (days) {
-            const date = new Date();
-            date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));
-            expires = '; expires=' + date.toUTCString();
-        }
-        document.cookie = name + '=' + value + expires + '; path=/';
-    }
-    private static readCookie(name: string): string | null {
-        const nameEq = name + '=';
-        const ca = document.cookie.split(';');
-        for (let c of ca) {
-            while (c.charAt(0) === ' ') {
-                c = c.substring(1, c.length);
-            }
-            if (c.indexOf(nameEq) === 0) {
-                return c.substring(nameEq.length, c.length);
-            }
-        }
-        return null;
-    }
-}
-export class InMemoryPersister implements UserSessionPersister {
-    private endOfLife: number = 0;
-    private storage: string = '';
-    public loadUserSession() {
-        return !this.endOfLife || (Date.now() > this.endOfLife) ? '' : this.storage;
-    }
-    public saveUserSession(userSession: string, daysToLive: number) {
-        this.storage = userSession;
-        this.endOfLife = Date.now() + (daysToLive*24*60*60*1000);
-    }
-}
\ No newline at end of file