diff --git a/Sources/SafeDICore/Models/TypeDescription.swift b/Sources/SafeDICore/Models/TypeDescription.swift
index 24e564dc..bff741dd 100644
--- a/Sources/SafeDICore/Models/TypeDescription.swift
+++ b/Sources/SafeDICore/Models/TypeDescription.swift
@@ -200,7 +200,7 @@ public enum TypeDescription: Codable, Hashable, Comparable, Sendable {
         }
     }
 
-    var isOptional: Bool {
+    public var isOptional: Bool {
         switch self {
         case .any,
                 .array,
@@ -438,10 +438,17 @@ extension ExprSyntax {
             genericTypeVisitor.walk(genericExpr.genericArgumentClause)
             switch genericExpr.expression.typeDescription {
             case let .simple(name, _):
-                return .simple(
-                    name: name,
-                    generics: genericTypeVisitor.genericArguments
-                )
+                if name == "Optional",
+                   genericTypeVisitor.genericArguments.count == 1,
+                   let firstGenericArgument = genericTypeVisitor.genericArguments.first
+                {
+                    return .optional(firstGenericArgument)
+                } else {
+                    return .simple(
+                        name: name,
+                        generics: genericTypeVisitor.genericArguments
+                    )
+                }
             case let .nested(name, parentType, _):
                 return .nested(
                     name: name,
diff --git a/Sources/SafeDIMacros/Macros/InstantiableMacro.swift b/Sources/SafeDIMacros/Macros/InstantiableMacro.swift
index 4eda247f..dabde52d 100644
--- a/Sources/SafeDIMacros/Macros/InstantiableMacro.swift
+++ b/Sources/SafeDIMacros/Macros/InstantiableMacro.swift
@@ -35,7 +35,14 @@ public struct InstantiableMacro: MemberMacro {
                 declaration.attributes.instantiableMacro
             )?.fulfillingAdditionalTypes
         {
-            if ArrayExprSyntax(fulfillingAdditionalTypesArgument) == nil {
+            if let arrayExpression = ArrayExprSyntax(fulfillingAdditionalTypesArgument) {
+                if arrayExpression
+                    .elements
+                .contains(where: { $0.expression.typeDescription.isOptional })
+                {
+                    throw InstantiableError.fulfillingAdditionalTypesContainsOptional
+                }
+            } else {
                 throw InstantiableError.fulfillingAdditionalTypesArgumentInvalid
             }
         }
@@ -339,6 +346,7 @@ public struct InstantiableMacro: MemberMacro {
 
     private enum InstantiableError: Error, CustomStringConvertible {
         case decoratingIncompatibleType
+        case fulfillingAdditionalTypesContainsOptional
         case fulfillingAdditionalTypesArgumentInvalid
         case tooManyInstantiateMethods
 
@@ -346,6 +354,8 @@ public struct InstantiableMacro: MemberMacro {
             switch self {
             case .decoratingIncompatibleType:
                 "@\(InstantiableVisitor.macroName) must decorate an extension on a type or a class, struct, or actor declaration"
+            case .fulfillingAdditionalTypesContainsOptional:
+                "The argument `fulfillingAdditionalTypes` must not include optionals"
             case .fulfillingAdditionalTypesArgumentInvalid:
                 "The argument `fulfillingAdditionalTypes` must be an inlined array"
             case .tooManyInstantiateMethods:
diff --git a/Tests/SafeDIMacrosTests/InstantiableMacroTests.swift b/Tests/SafeDIMacrosTests/InstantiableMacroTests.swift
index ae7f6a23..2ca6fe30 100644
--- a/Tests/SafeDIMacrosTests/InstantiableMacroTests.swift
+++ b/Tests/SafeDIMacrosTests/InstantiableMacroTests.swift
@@ -777,14 +777,46 @@ final class InstantiableMacroTests: XCTestCase {
         assertMacro {
             """
             @Instantiable
-            public enum ExampleService {}
+            public enum ExampleService: Instantiable {}
             """
         } diagnostics: {
             """
             @Instantiable
             ┬────────────
             ╰─ 🛑 @Instantiable must decorate an extension on a type or a class, struct, or actor declaration
-            public enum ExampleService {}
+            public enum ExampleService: Instantiable {}
+            """
+        }
+    }
+
+    func test_declaration_throwsErrorWhenFulfillingAdditionalTypesIncludesAShortformOptional() {
+        assertMacro {
+            """
+            @Instantiable(fulfillingAdditionalTypes: [AnyObject?.self])
+            public final class ExampleService: Instantiable {}
+            """
+        } diagnostics: {
+            """
+            @Instantiable(fulfillingAdditionalTypes: [AnyObject?.self])
+            ┬──────────────────────────────────────────────────────────
+            ╰─ 🛑 The argument `fulfillingAdditionalTypes` must not include optionals
+            public final class ExampleService: Instantiable {}
+            """
+        }
+    }
+
+    func test_declaration_throwsErrorWhenFulfillingAdditionalTypesIncludesALongformOptional() {
+        assertMacro {
+            """
+            @Instantiable(fulfillingAdditionalTypes: [Optional<AnyObject>.self])
+            public final class ExampleService: Instantiable {}
+            """
+        } diagnostics: {
+            """
+            @Instantiable(fulfillingAdditionalTypes: [Optional<AnyObject>.self])
+            ┬───────────────────────────────────────────────────────────────────
+            ╰─ 🛑 The argument `fulfillingAdditionalTypes` must not include optionals
+            public final class ExampleService: Instantiable {}
             """
         }
     }
@@ -794,7 +826,7 @@ final class InstantiableMacroTests: XCTestCase {
             """
             let fulfillingAdditionalTypes: [Any.Type] = [AnyObject.self]
             @Instantiable(fulfillingAdditionalTypes: fulfillingAdditionalTypes)
-            public final class ExampleService {}
+            public final class ExampleService: Instantiable {}
             """
         } diagnostics: {
             """
@@ -802,7 +834,7 @@ final class InstantiableMacroTests: XCTestCase {
             @Instantiable(fulfillingAdditionalTypes: fulfillingAdditionalTypes)
             ┬──────────────────────────────────────────────────────────────────
             ╰─ 🛑 The argument `fulfillingAdditionalTypes` must be an inlined array
-            public final class ExampleService {}
+            public final class ExampleService: Instantiable {}
             """
         }
     }
@@ -811,14 +843,14 @@ final class InstantiableMacroTests: XCTestCase {
         assertMacro {
             """
             @Instantiable(fulfillingAdditionalTypes: { [AnyObject.self] }())
-            public final class ExampleService {}
+            public final class ExampleService: Instantiable {}
             """
         } diagnostics: {
             """
             @Instantiable(fulfillingAdditionalTypes: { [AnyObject.self] }())
             ┬───────────────────────────────────────────────────────────────
             ╰─ 🛑 The argument `fulfillingAdditionalTypes` must be an inlined array
-            public final class ExampleService {}
+            public final class ExampleService: Instantiable {}
             """
         }
     }