diff --git a/AspNetIdentity.WebApi/Controllers/AccountsController.cs b/AspNetIdentity.WebApi/Controllers/AccountsController.cs
index 05807c8..712264d 100644
--- a/AspNetIdentity.WebApi/Controllers/AccountsController.cs
+++ b/AspNetIdentity.WebApi/Controllers/AccountsController.cs
@@ -184,7 +184,7 @@ public async Task<IHttpActionResult> AssignRolesToUser([FromUri] string id, [Fro
             
             var currentRoles = await this.AppUserManager.GetRolesAsync(appUser.Id);
 
-            var rolesNotExists = rolesToAssign.Except(this.AppRoleManager.Roles.Select(x => x.Name)).ToArray();
+            var rolesNotExists = rolesToAssign.Except(this.AppRoleManager.Roles.Select(x => x.Name), StringComparer.OrdinalIgnoreCase).ToArray();
 
             if (rolesNotExists.Count() > 0) {
 
@@ -272,4 +272,4 @@ public async Task<IHttpActionResult> RemoveClaimsFromUser([FromUri] string id, [
         }
 
     }
-}
\ No newline at end of file
+}