diff --git a/src/RecurrentTasks/RecurrentTasks.csproj b/src/RecurrentTasks/RecurrentTasks.csproj
index 038c898..73d068c 100644
--- a/src/RecurrentTasks/RecurrentTasks.csproj
+++ b/src/RecurrentTasks/RecurrentTasks.csproj
@@ -1,21 +1,22 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <Copyright>Dmitry Popov, 2016-2018</Copyright>
+    <Copyright>Dmitry Popov, 2016-2019</Copyright>
     <AssemblyTitle>RecurrentTasks</AssemblyTitle>
     <TargetFramework>netstandard2.0</TargetFramework>
     <AssemblyName>RecurrentTasks</AssemblyName>
     <PackageId>RecurrentTasks</PackageId>
     <PackageTags>task;job;recurrent;recurring;aspnetcore</PackageTags>
-    <PackageReleaseNotes>https://github.com/justdmitry/RecurrentTasks/releases/tag/v6.0.0</PackageReleaseNotes>
+    <PackageReleaseNotes>https://github.com/justdmitry/RecurrentTasks/releases/tag/v6.1.0</PackageReleaseNotes>
     <PackageProjectUrl>https://github.com/justdmitry/RecurrentTasks</PackageProjectUrl>
-    <PackageLicenseUrl>https://github.com/justdmitry/RecurrentTasks/blob/master/LICENSE</PackageLicenseUrl>
+    <PackageLicenseUrl></PackageLicenseUrl>
     <RepositoryType>git</RepositoryType>
     <RepositoryUrl>https://github.com/justdmitry/RecurrentTasks.git</RepositoryUrl>
-    <Version>6.0.2</Version>
+    <Version>6.1.0</Version>
     <Description>RecurrentTasks for .NET allows you to run simple recurrent background tasks with specific intervals, without complex frameworks, persistance, etc...</Description>
     <Authors>just_dmitry</Authors>
     <Company />
     <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
+    <PackageLicenseExpression>MIT</PackageLicenseExpression>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(Configuration)'=='Debug'">
diff --git a/src/RecurrentTasks/RecurrentTasksServiceCollectionExtensions.cs b/src/RecurrentTasks/RecurrentTasksServiceCollectionExtensions.cs
index a9264b7..27d363d 100644
--- a/src/RecurrentTasks/RecurrentTasksServiceCollectionExtensions.cs
+++ b/src/RecurrentTasks/RecurrentTasksServiceCollectionExtensions.cs
@@ -20,8 +20,8 @@ public static IServiceCollection AddTask<TRunnable>(
 
             var runnableType = typeof(TRunnable);
 
-            // Register TRunnable in DI container, if not registered already
-            if (!services.Any(x => x.ServiceType == runnableType))
+            // Register TRunnable (if not an interface or abstract class) in DI container, if not registered already
+            if (!runnableType.IsAbstract && !services.Any(x => x.ServiceType == runnableType))
             {
                 services.Add(new ServiceDescriptor(runnableType, runnableType, runnableLifetime));
             }