diff --git a/external/FluentIL b/external/FluentIL
index 3998b823..6140c539 160000
--- a/external/FluentIL
+++ b/external/FluentIL
@@ -1 +1 @@
-Subproject commit 3998b8238d0eeea467c71df70781693b07e01309
+Subproject commit 6140c5396e5358c16e72b69ec85b370a9e92a1ea
diff --git a/src/AspectInjector.Core/Models/AspectDefinition.cs b/src/AspectInjector.Core/Models/AspectDefinition.cs
index 4254c1d4..238c87d8 100644
--- a/src/AspectInjector.Core/Models/AspectDefinition.cs
+++ b/src/AspectInjector.Core/Models/AspectDefinition.cs
@@ -47,7 +47,7 @@ public bool Validate(ILogger log)
         {
             var result = true;
 
-            if(Scope!= Scope.Global && Scope!= Scope.PerInstance)
+            if (Scope != Scope.Global && Scope != Scope.PerInstance)
                 log.Log(GeneralRules.UnknownCompilationOption, Host, GeneralRules.Literals.UnknownAspectScope(Scope.ToString()));
 
             if (!Effects.Any())
@@ -59,6 +59,12 @@ public bool Validate(ILogger log)
                 result = false;
             }
 
+            if (!Host.IsPublic && !Host.IsNestedPublic)
+            {
+                log.Log(AspectRules.AspectMustHaveValidSignature, Host, Host.Name, AspectRules.Literals.IsNotPublic);
+                result = false;
+            }
+
             if (Host.IsAbstract)
             {
                 if (Host.IsSealed)
diff --git a/src/AspectInjector.Rules/AspectRules.cs b/src/AspectInjector.Rules/AspectRules.cs
index ce5a478d..6e23bcc2 100644
--- a/src/AspectInjector.Rules/AspectRules.cs
+++ b/src/AspectInjector.Rules/AspectRules.cs
@@ -8,6 +8,7 @@ public static class Literals
         {
             public static readonly string HasGenericParams = "has generic parameters";
             public static readonly string IsAbstract = "is abstract";
+            public static readonly string IsNotPublic = "is not public";
             public static readonly string IsStatic = "is static";
         }
 
@@ -20,9 +21,9 @@ public static class Literals
 
         public static readonly Rule AspectMustHaveValidSignature =
             GeneralRules.Make("AI_A001",
-               "Aspect must not be generic, abstract or static",
+               "Aspect must not be generic, abstract or static. And it should be public.",
                "Aspect '{0}' {1}",
-               "Aspect must have valid signature. Aspect must be non-generic, non-abstract and non-static class.");
+               "Aspect must have valid signature. Aspect must be non-generic, non-abstract and non-static public class.");
 
         public static readonly Rule AspectFactoryMustContainFactoryMethod =
             GeneralRules.Make("AI_A002",
diff --git a/tests/AspectInjector.Tests.Runtime/Advices/AccessModifiersTests.cs b/tests/AspectInjector.Tests.Runtime/Advices/AccessModifiersTests.cs
index 368afba5..6d16fb5d 100644
--- a/tests/AspectInjector.Tests.Runtime/Advices/AccessModifiersTests.cs
+++ b/tests/AspectInjector.Tests.Runtime/Advices/AccessModifiersTests.cs
@@ -37,7 +37,7 @@ public void Public() { }
 
         [Aspect(Scope.Global)]
         [Injection(typeof(AccessTestAspect))]
-        internal class AccessTestAspect : Attribute
+        public class AccessTestAspect : Attribute
         {
             [Advice(Kind.Around, Targets = Target.Internal)]
             public object TestAccess([Argument(Source.Metadata)] MethodBase method)
diff --git a/tests/AspectInjector.Tests.Runtime/Advices/AfterTests.cs b/tests/AspectInjector.Tests.Runtime/Advices/AfterTests.cs
index a9c2572e..ac04ee66 100644
--- a/tests/AspectInjector.Tests.Runtime/Advices/AfterTests.cs
+++ b/tests/AspectInjector.Tests.Runtime/Advices/AfterTests.cs
@@ -138,7 +138,7 @@ public int TestCustomSetterProperty
     //aspects
     [Aspect(Scope.Global)]
     [Injection(typeof(AfterTests_AfterMethodAspect))]
-    internal class AfterTests_AfterMethodAspect : Attribute
+    public class AfterTests_AfterMethodAspect : Attribute
     {
         //Property
         [Advice(Kind.After, Targets = Target.Setter)]
@@ -161,7 +161,7 @@ internal class AfterTests_AfterMethodAspect : Attribute
 
     [Aspect(Scope.Global)]
     [Injection(typeof(AfterTests_AfterConstructorAspect))]
-    internal class AfterTests_AfterConstructorAspect : Attribute
+    public class AfterTests_AfterConstructorAspect : Attribute
     {
         [Advice(Kind.After, Targets = Target.Constructor)]
         public void AfterConstructor() { Checker.Passed = true; }
diff --git a/tests/AspectInjector.Tests.Runtime/Advices/ArgumentsTests.cs b/tests/AspectInjector.Tests.Runtime/Advices/ArgumentsTests.cs
index f9a35bff..f3ae916a 100644
--- a/tests/AspectInjector.Tests.Runtime/Advices/ArgumentsTests.cs
+++ b/tests/AspectInjector.Tests.Runtime/Advices/ArgumentsTests.cs
@@ -132,7 +132,7 @@ public void Fact()
 
         [Aspect(Scope.Global)]
         [Injection(typeof(ArgumentsTests_InstanceAspect))]
-        internal class ArgumentsTests_InstanceAspect : Attribute
+        public class ArgumentsTests_InstanceAspect : Attribute
         {
             [Advice(Kind.Before, Targets = Target.Method)]
             public void BeforeMethod([Argument(Source.Instance)] object instance)
@@ -151,7 +151,7 @@ public static void Fact()
 
         [Aspect(Scope.Global)]
         [Injection(typeof(ArgumentsTests_StaticInstanceAspect))]
-        internal class ArgumentsTests_StaticInstanceAspect:Attribute
+        public class ArgumentsTests_StaticInstanceAspect:Attribute
         {
             [Advice(Kind.Before, Targets = Target.Method)]
             public void BeforeMethod([Argument(Source.Instance)] object instance)
@@ -170,7 +170,7 @@ public static void Fact()
 
         [Aspect(Scope.Global)]
         [Injection(typeof(ArgumentsTests_ReturnTypeAspect))]
-        internal class ArgumentsTests_ReturnTypeAspect: Attribute
+        public class ArgumentsTests_ReturnTypeAspect: Attribute
         {
             [Advice(Kind.Before, Targets = Target.Method)]
             public void BeforeMethod([Argument(Source.Type)] System.Type type)
@@ -197,7 +197,7 @@ static ArgumentsTests_StaticConstructorTarget()
 
         [Aspect(Scope.Global)]
         [Injection(typeof(ArgumentsTests_StaticMethodAspect))]
-        internal class ArgumentsTests_StaticMethodAspect : Attribute
+        public class ArgumentsTests_StaticMethodAspect : Attribute
         {
             [Advice(Kind.Before, Targets = Target.Method | Target.Constructor)]
             public void BeforeMethod([Argument(Source.Metadata)] MethodBase method)
@@ -245,7 +245,7 @@ public ArgumentsTests_ConstructorTarget()
 
         [Aspect(Scope.Global)]
         [Injection(typeof(ArgumentsTests_MethodAspect))]
-        internal class ArgumentsTests_MethodAspect:Attribute
+        public class ArgumentsTests_MethodAspect:Attribute
         {
             [Advice(Kind.Before, Targets = Target.Method | Target.Constructor)]
             public void BeforeMethod([Argument(Source.Metadata)] MethodBase method)
@@ -266,7 +266,7 @@ public void Fact(object obj, ref object objRef, out object objOut, int value, re
 
         [Aspect(Scope.Global)]
         [Injection(typeof(ArgumentsTests_ArgumentsAspect))]
-        internal class ArgumentsTests_ArgumentsAspect:Attribute
+        public class ArgumentsTests_ArgumentsAspect:Attribute
         {
             [Advice(Kind.Before, Targets = Target.Method)]
             public void BeforeMethod([Argument(Source.Arguments)] object[] args)
@@ -287,7 +287,7 @@ public static void Fact(int a, string b)
 
         [Aspect(Scope.Global)]
         [Injection(typeof(ArgumentsTests_StaticArgumentsAspect))]
-        internal class ArgumentsTests_StaticArgumentsAspect :Attribute
+        public class ArgumentsTests_StaticArgumentsAspect :Attribute
         {
             [Advice(Kind.Before, Targets = Target.Method)]
             public void BeforeMethod([Argument(Source.Arguments)] object[] args)
@@ -306,7 +306,7 @@ public void Fact()
 
         [Aspect(Scope.Global)]
         [Injection(typeof(ArgumentsTests_AroundMethodAspect))]
-        internal class ArgumentsTests_AroundMethodAspect : Attribute
+        public class ArgumentsTests_AroundMethodAspect : Attribute
         {
             [Advice(Kind.Around, Targets = Target.Method)]
             public object BeforeMethod([Argument(Source.Metadata)] MethodBase method)
@@ -327,7 +327,7 @@ public object Fact()
 
         [Aspect(Scope.Global)]
         [Injection(typeof(ArgumentsTests_AroundRetValAspect))]
-        internal class ArgumentsTests_AroundRetValAspect:Attribute
+        public class ArgumentsTests_AroundRetValAspect:Attribute
         {
             [Advice(Kind.After, Targets = Target.Method)]
             public void AfterMethod([Argument(Source.ReturnValue)] object ret)
@@ -344,7 +344,7 @@ internal class ArgumentsTests_PropertyTarget
 
         [Injection(typeof(ArgumentsTests_PropertyTarget_Aspect))]
         [Aspect(Scope.Global)]
-        class ArgumentsTests_PropertyTarget_Aspect : Attribute
+        public class ArgumentsTests_PropertyTarget_Aspect : Attribute
         {
             [Advice(Kind.Before)]
             public void TestName([Argument(Source.Name)] string name)
diff --git a/tests/AspectInjector.Tests.Runtime/Advices/AroundTests.cs b/tests/AspectInjector.Tests.Runtime/Advices/AroundTests.cs
index aad97215..216ffb6f 100644
--- a/tests/AspectInjector.Tests.Runtime/Advices/AroundTests.cs
+++ b/tests/AspectInjector.Tests.Runtime/Advices/AroundTests.cs
@@ -189,7 +189,7 @@ public T Generic<T>(T data)
 
         [Aspect(Scope.Global)]
         [Injection(typeof(AroundTests_Simple))]
-        internal class AroundTests_Simple : Attribute
+        public class AroundTests_Simple : Attribute
         {
             [Advice(Kind.Around, Targets = Target.Method)]
             public object AroundMethod([Argument(Source.Target)] Func<object[], object> target,
@@ -201,7 +201,7 @@ public object AroundMethod([Argument(Source.Target)] Func<object[], object> targ
 
         [Aspect(Scope.Global)]
         [Injection(typeof(AroundTests_Aspect1))]
-        internal class AroundTests_Aspect1 : Attribute
+        public class AroundTests_Aspect1 : Attribute
         {
             [Advice(Kind.Around, Targets = Target.Method)]
             public object AroundMethod([Argument(Source.Target)] Func<object[], object> target,
@@ -213,7 +213,7 @@ public object AroundMethod([Argument(Source.Target)] Func<object[], object> targ
 
         [Aspect(Scope.Global)]
         [Injection(typeof(AroundTests_Aspect2))]
-        internal class AroundTests_Aspect2 : Attribute
+        public class AroundTests_Aspect2 : Attribute
         {
             [Advice(Kind.Around, Targets = Target.Method)]
             public object AroundMethod([Argument(Source.Target)] Func<object[], object> target,
@@ -235,7 +235,7 @@ public void Fact(ref int i)
 
         [Aspect(Scope.Global)]
         [Injection(typeof(AroundTests_ArgumentsModificationAspect))]
-        internal class AroundTests_ArgumentsModificationAspect : Attribute
+        public class AroundTests_ArgumentsModificationAspect : Attribute
         {
             [Advice(Kind.Around, Targets = Target.Method)]
             public object AroundMethod(
diff --git a/tests/AspectInjector.Tests.Runtime/Advices/BeforeTests.cs b/tests/AspectInjector.Tests.Runtime/Advices/BeforeTests.cs
index 90f0cedf..e22442dc 100644
--- a/tests/AspectInjector.Tests.Runtime/Advices/BeforeTests.cs
+++ b/tests/AspectInjector.Tests.Runtime/Advices/BeforeTests.cs
@@ -99,7 +99,7 @@ public void Fact(string data)
     //aspects
     [Aspect(Scope.Global)]
     [Injection(typeof(BeforeTests_Aspect))]
-    internal class BeforeTests_Aspect : Attribute
+    public class BeforeTests_Aspect : Attribute
     {
         //Property
         [Advice(Kind.Before, Targets = Target.Setter)]
@@ -122,7 +122,7 @@ internal class BeforeTests_Aspect : Attribute
 
     [Aspect( Scope.Global)]
     [Injection(typeof(BeforeTests_BeforeConstructorAspect))]
-    internal class BeforeTests_BeforeConstructorAspect : Attribute
+    public class BeforeTests_BeforeConstructorAspect : Attribute
     {
         [Advice(Kind.Before, Targets = Target.Constructor)]
         public void BeforeConstructor([Argument(Source.Instance)] object instance)
@@ -135,7 +135,7 @@ public void BeforeConstructor([Argument(Source.Instance)] object instance)
     [Mixin(typeof(IDisposable))]
     [Aspect(Scope.Global)]
     [Injection(typeof(BeforeTests_BeforeConstructorWithInterfaceAspect))]
-    internal class BeforeTests_BeforeConstructorWithInterfaceAspect : Attribute, IDisposable
+    public class BeforeTests_BeforeConstructorWithInterfaceAspect : Attribute, IDisposable
     {
         [Advice(Kind.Before, Targets = Target.Constructor)]
         public void BeforeConstructor() { Checker.Passed = true; }
diff --git a/tests/AspectInjector.Tests.Runtime/Advices/GenericTests.cs b/tests/AspectInjector.Tests.Runtime/Advices/GenericTests.cs
index 6a310c9f..7639522e 100644
--- a/tests/AspectInjector.Tests.Runtime/Advices/GenericTests.cs
+++ b/tests/AspectInjector.Tests.Runtime/Advices/GenericTests.cs
@@ -59,7 +59,7 @@ public void TestGenericMethod<U>()
 
     [Aspect(Scope.Global)]
     [Injection(typeof(GenericTests_Aspect))]
-    internal class GenericTests_Aspect : Attribute
+    public class GenericTests_Aspect : Attribute
     {
         [Advice(Kind.Before, Targets = Target.Method)]
         public void BeforeMethod() { Checker.Passed = true; }
@@ -80,7 +80,7 @@ public void Fact()
 
     [Aspect(Scope.Global)]
     [Injection(typeof(GenericTests_OpenGenericAspect))]
-    internal class GenericTests_OpenGenericAspect:Attribute
+    public class GenericTests_OpenGenericAspect:Attribute
     {
         [Advice(Kind.Before, Targets = Target.Method)]
         public void BeforeMethod() { Checker.Passed = true; }
@@ -98,7 +98,7 @@ public T Fact<T>(ref T value)
 
     [Aspect(Scope.Global)]
     [Injection(typeof(GenericAroundTests_Aspect))]
-    internal class GenericAroundTests_Aspect : Attribute
+    public class GenericAroundTests_Aspect : Attribute
     {
         [Advice(Kind.Around, Targets = Target.Method)]
         public object AroundAdvice([Argument(Source.Target)] Func<object[], object> target,
diff --git a/tests/AspectInjector.Tests.Runtime/Advices/OrderTests.cs b/tests/AspectInjector.Tests.Runtime/Advices/OrderTests.cs
index cf90f066..0c02a0c9 100644
--- a/tests/AspectInjector.Tests.Runtime/Advices/OrderTests.cs
+++ b/tests/AspectInjector.Tests.Runtime/Advices/OrderTests.cs
@@ -31,7 +31,7 @@ public void Fact()
         class Trigger : Attribute { }
 
         [Aspect(Scope.Global)]
-        internal class OrderTests_Aspect1
+        public class OrderTests_Aspect1
         {
             [Advice(Kind.Before)]
             public void BeforeMethod()
@@ -41,7 +41,7 @@ public void BeforeMethod()
         }
 
         [Aspect(Scope.Global)]
-        internal class OrderTests_Aspect2
+        public class OrderTests_Aspect2
         {
             [Advice(Kind.Before)]
             public void BeforeMethod()
@@ -51,7 +51,7 @@ public void BeforeMethod()
         }
 
         [Aspect(Scope.Global)]
-        internal class OrderTests_Aspect3
+        public class OrderTests_Aspect3
         {
             [Advice(Kind.Before)]
             public void BeforeMethod()
diff --git a/tests/AspectInjector.Tests.Runtime/Advices/StaticTests.cs b/tests/AspectInjector.Tests.Runtime/Advices/StaticTests.cs
index 7a99d38c..dced1430 100644
--- a/tests/AspectInjector.Tests.Runtime/Advices/StaticTests.cs
+++ b/tests/AspectInjector.Tests.Runtime/Advices/StaticTests.cs
@@ -45,7 +45,7 @@ public static int Do123(int data, StringBuilder sb, object to, bool passed, bool
 
         [Aspect(Scope.Global)]
         [Injection(typeof(StaticTests_AroundAspect1))]
-        internal class StaticTests_AroundAspect1 : Attribute
+        public class StaticTests_AroundAspect1 : Attribute
         {
             [Advice(Kind.Around, Targets = Target.Method)]
             public object AroundMethod([Argument(Source.Target)] Func<object[], object> target,
@@ -57,7 +57,7 @@ public object AroundMethod([Argument(Source.Target)] Func<object[], object> targ
 
         [Aspect(Scope.Global)]
         [Injection(typeof(StaticTests_AroundAspect2))]
-        internal class StaticTests_AroundAspect2 : Attribute
+        public class StaticTests_AroundAspect2 : Attribute
         {
             [Advice(Kind.Around, Targets = Target.Method)]
             public object AroundMethod([Argument(Source.Target)] Func<object[], object> target,
@@ -81,7 +81,7 @@ public void TestInstanceMethod()
 
         [Aspect(Scope.Global)]
         [Injection(typeof(StaticTests_BeforeAspect))]
-        internal class StaticTests_BeforeAspect : Attribute
+        public class StaticTests_BeforeAspect : Attribute
         {
             //Property
             [Advice(Kind.Before, Targets = Target.Method)]
diff --git a/tests/AspectInjector.Tests.Runtime/General/AspectScopeTests.cs b/tests/AspectInjector.Tests.Runtime/General/AspectScopeTests.cs
index 628f847e..07fda117 100644
--- a/tests/AspectInjector.Tests.Runtime/General/AspectScopeTests.cs
+++ b/tests/AspectInjector.Tests.Runtime/General/AspectScopeTests.cs
@@ -31,7 +31,7 @@ public void SCOPE_Create_Global_Aspect()
 
     [Aspect(Scope.PerInstance)]
     [Injection(typeof(AspectScopeTests_PerInstanceAspect))]
-    internal class AspectScopeTests_PerInstanceAspect:Attribute
+    public class AspectScopeTests_PerInstanceAspect:Attribute
     {
         public static int _counter;
 
@@ -48,7 +48,7 @@ public void Do()
 
     [Aspect(Scope.Global)]
     [Injection(typeof(AspectScopeTests_GlobalAspect))]
-    internal class AspectScopeTests_GlobalAspect: Attribute
+    public class AspectScopeTests_GlobalAspect: Attribute
     {
         public static int _counter;
 
diff --git a/tests/AspectInjector.Tests.Runtime/General/UnmanagedTests.cs b/tests/AspectInjector.Tests.Runtime/General/UnmanagedTests.cs
index 40d44ea4..251133f7 100644
--- a/tests/AspectInjector.Tests.Runtime/General/UnmanagedTests.cs
+++ b/tests/AspectInjector.Tests.Runtime/General/UnmanagedTests.cs
@@ -14,7 +14,7 @@ public class UnmanagedTests
 
     [Aspect(Scope.Global)]
     [Injection(typeof(UnmanagedTests_Aspect))]
-    internal class UnmanagedTests_Aspect : Attribute
+    public class UnmanagedTests_Aspect : Attribute
     {
         [Advice(Kind.After, Targets = Target.Method)]
         public void Trace()
diff --git a/tests/AspectInjector.Tests.Runtime/Injections/DirectInjectionsTests.cs b/tests/AspectInjector.Tests.Runtime/Injections/DirectInjectionsTests.cs
index 806f84e0..69c2ebc7 100644
--- a/tests/AspectInjector.Tests.Runtime/Injections/DirectInjectionsTests.cs
+++ b/tests/AspectInjector.Tests.Runtime/Injections/DirectInjectionsTests.cs
@@ -23,7 +23,7 @@ private class TestTarget
 
         [Aspect(Scope.Global)]
         [Injection(typeof(TestAspect))]
-        private class TestAspect : Attribute
+        public class TestAspect : Attribute
         {
             private int _count = 0;
 
diff --git a/tests/AspectInjector.Tests.Runtime/Injections/InjectionOrderTests.cs b/tests/AspectInjector.Tests.Runtime/Injections/InjectionOrderTests.cs
index a64c92d6..8ae52eb1 100644
--- a/tests/AspectInjector.Tests.Runtime/Injections/InjectionOrderTests.cs
+++ b/tests/AspectInjector.Tests.Runtime/Injections/InjectionOrderTests.cs
@@ -18,7 +18,7 @@ public void AspectInstance_InHierarchy_MustBeOne()
 
         [Aspect(Scope.PerInstance)]
         [Injection(typeof(TestAspect))]
-        private class TestAspect : Attribute
+        public class TestAspect : Attribute
         {
             public int Count { get; private set; }
 
diff --git a/tests/AspectInjector.Tests.Runtime/Injections/SkipInjectionsTests.cs b/tests/AspectInjector.Tests.Runtime/Injections/SkipInjectionsTests.cs
index e59e001a..e6caf45f 100644
--- a/tests/AspectInjector.Tests.Runtime/Injections/SkipInjectionsTests.cs
+++ b/tests/AspectInjector.Tests.Runtime/Injections/SkipInjectionsTests.cs
@@ -39,7 +39,7 @@ public void Test() { }
         }
 
         [Aspect(Scope.Global)]
-        private class TestAspect
+        public class TestAspect
         {
             [Advice(Kind.Before, Targets = Target.Method)]
             public void Before()
diff --git a/tests/AspectInjector.Tests.Runtime/Interfaces/GeneralTests.cs b/tests/AspectInjector.Tests.Runtime/Interfaces/GeneralTests.cs
index 2eb833c9..91014b27 100644
--- a/tests/AspectInjector.Tests.Runtime/Interfaces/GeneralTests.cs
+++ b/tests/AspectInjector.Tests.Runtime/Interfaces/GeneralTests.cs
@@ -121,7 +121,7 @@ private class GeneralTests_Trigger : Attribute
         [Mixin(typeof(IGeneralTests))]
         [Mixin(typeof(INotifyPropertyChanged))]
         [Aspect(Scope.Global)]
-        internal class GeneralTests_Aspect : IGeneralTests, INotifyPropertyChanged
+        public class GeneralTests_Aspect : IGeneralTests, INotifyPropertyChanged
         {
             public event PropertyChangedEventHandler PropertyChanged = (s, e) => { };
 
diff --git a/tests/AspectInjector.Tests.Runtime/Issues/0098.cs b/tests/AspectInjector.Tests.Runtime/Issues/0098.cs
index 7f5647de..cc3457c7 100644
--- a/tests/AspectInjector.Tests.Runtime/Issues/0098.cs
+++ b/tests/AspectInjector.Tests.Runtime/Issues/0098.cs
@@ -14,7 +14,7 @@ public void Fixed()
 
         [Aspect(Scope.PerInstance)]
         [Injection(typeof(TestAspect))]
-        private class TestAspect : Attribute
+        public class TestAspect : Attribute
         {
             [Advice(Kind.Before)]
             public void Before()