diff --git a/src/AST/Class.cs b/src/AST/Class.cs
index 45b535f5..e6129619 100644
--- a/src/AST/Class.cs
+++ b/src/AST/Class.cs
@@ -10,7 +10,8 @@ namespace CppSharp.AST
     {
         Private,
         Protected,
-        Public
+        Public,
+        Internal
     }
 
     // A C++ access specifier declaration.
diff --git a/src/Generator.Tests/Passes/TestPasses.cs b/src/Generator.Tests/Passes/TestPasses.cs
index 6a6de8c0..d9cb4189 100644
--- a/src/Generator.Tests/Passes/TestPasses.cs
+++ b/src/Generator.Tests/Passes/TestPasses.cs
@@ -191,5 +191,16 @@ namespace CppSharp.Generator.Tests.Passes
             Assert.IsTrue(constMethodWithParam.GenerationKind == GenerationKind.None);
             Assert.IsTrue(nonConstMethodWithParam.GenerationKind == GenerationKind.Generate);
         }
+
+        [Test]
+        public void TestSetMethodAsInternal()
+        {
+            var c = AstContext.Class("TestMethodAsInternal");
+            var method = c.Method("beInternal");
+            Assert.AreEqual(method.Access , AccessSpecifier.Public);
+            passBuilder.AddPass(new CheckMacroPass());
+            passBuilder.RunPasses(pass => pass.VisitLibrary(AstContext));
+            Assert.AreEqual(method.Access , AccessSpecifier.Internal);
+        }
     }
 }
diff --git a/src/Generator/Generators/CSharp/CSharpTextTemplate.cs b/src/Generator/Generators/CSharp/CSharpTextTemplate.cs
index f4f23459..ef0a2424 100644
--- a/src/Generator/Generators/CSharp/CSharpTextTemplate.cs
+++ b/src/Generator/Generators/CSharp/CSharpTextTemplate.cs
@@ -53,6 +53,7 @@ namespace CppSharp.Generators.CSharp
             switch (accessSpecifier)
             {
                 case AccessSpecifier.Private:
+                case AccessSpecifier.Internal:
                     return "internal ";
                 case AccessSpecifier.Protected:
                     return "protected ";
diff --git a/src/Generator/Passes/CheckMacrosPass.cs b/src/Generator/Passes/CheckMacrosPass.cs
index 26f2caa9..1946c30f 100644
--- a/src/Generator/Passes/CheckMacrosPass.cs
+++ b/src/Generator/Passes/CheckMacrosPass.cs
@@ -42,6 +42,10 @@ namespace CppSharp.Passes
     ///     CS_CONSTRAINT(TYPE [, TYPE]*) (templates)
     ///         Used to define constraint of generated generic type or generic method.
     /// 
+    ///     CS_INTERNAL (methods)
+    ///         Used to flag a method as internal to an assembly. So, it is
+    ///         not accessible outside that assembly.
+    /// 
     /// There isn't a standardized header provided by CppSharp so you will
     /// have to define these on your own.
     /// </summary>
@@ -155,6 +159,9 @@ namespace CppSharp.Passes
                 || e.Text == Prefix + "_EQUALS"))
                 method.ExplicitlyIgnore();
 
+            if (expansions.Any(e => e.Text == Prefix + "_INTERNAL"))
+                method.Access = AccessSpecifier.Internal;
+
             return base.VisitMethodDecl(method);
         }
 
diff --git a/tests/Native/Passes.h b/tests/Native/Passes.h
index eba7caf1..ee46e57c 100644
--- a/tests/Native/Passes.h
+++ b/tests/Native/Passes.h
@@ -61,3 +61,9 @@ struct TestCheckAmbiguousFunctionsPass
     int Method(int x);
     int Method(int x) const;
 };
+
+#define CS_INTERNAL
+struct TestMethodAsInternal
+{
+    int CS_INTERNAL beInternal();
+};