diff --git a/Package.swift b/Package.swift
index de8e5dc..584bc70 100644
--- a/Package.swift
+++ b/Package.swift
@@ -5,7 +5,8 @@ import PackageDescription
 let package = Package(
     name: "rorschach",
     platforms: [
-        .iOS(.v13)
+        .iOS(.v13),
+        .macOS(.v10_15)
     ],
     products: [
         .library(
diff --git a/Sources/Rorschach/Assertion.swift b/Sources/Rorschach/Assertion.swift
index 392f78d..c9dae76 100644
--- a/Sources/Rorschach/Assertion.swift
+++ b/Sources/Rorschach/Assertion.swift
@@ -12,14 +12,24 @@ import XCTest
 public struct Assertion {
 
     let title: String?
-    private let content: () -> Void
+    private var content: (() -> Void)?
+    private var asyncThrowingContent: (() async throws -> Void)?
+
+    public init(_ title: String? = nil, content: @escaping () async throws -> Void) {
+        self.title = title
+        self.asyncThrowingContent = content
+    }
 
     public init(_ title: String? = nil, content: @escaping () -> Void) {
         self.title = title
         self.content = content
     }
 
+    public func assert() async throws {
+        try await asyncThrowingContent?()
+    }
+
     public func assert() {
-        content()
+        content?()
     }
 }
diff --git a/Sources/Rorschach/Then.swift b/Sources/Rorschach/Then.swift
index 4dd6ee5..6d98ac7 100644
--- a/Sources/Rorschach/Then.swift
+++ b/Sources/Rorschach/Then.swift
@@ -21,6 +21,11 @@ public struct Then {
     }
     var contentOnlyTitle: String?
 
+    public init(_ title: String, content: @escaping () async throws -> Void) {
+        contentOnlyTitle = title
+        assertion = Assertion(content: content)
+    }
+
     public init(_ title: String, content: @escaping () -> Void) {
         contentOnlyTitle = title
         assertion = Assertion(content: content)
@@ -30,7 +35,7 @@ public struct Then {
         assertion = content()
     }
 
-    func assert() {
-        assertion?.assert()
+    func assert() async throws {
+        try await assertion?.assert()
     }
 }
diff --git a/Sources/Rorschach/XCTestCase+BDDStyle.swift b/Sources/Rorschach/XCTestCase+BDDStyle.swift
index 8e367b8..4ed4fd5 100644
--- a/Sources/Rorschach/XCTestCase+BDDStyle.swift
+++ b/Sources/Rorschach/XCTestCase+BDDStyle.swift
@@ -32,7 +32,7 @@ public protocol Expecting {
     ///        }
     ///    }
     ///    ```
-    func expect(@ExpectationBuilder _ content: () -> (given: Given, when: When, then: Then))
+    func expect(@ExpectationBuilder _ content: @escaping () -> (given: Given, when: When, then: Then))
 
     /// A test's expectation containing only the ``When`` and the ``Then`` sections.
     ///
@@ -49,13 +49,13 @@ public protocol Expecting {
     ///    }
     ///    ```
 
-    func expect(@ExpectationBuilder _ content: () -> (when: When, then: Then))
+    func expect(@ExpectationBuilder _ content: @escaping () -> (when: When, then: Then))
 }
 
 /// This extension adds support for test expectations to _XCTestCase_.
 extension XCTestCase: Expecting {
 
-    public func expect(@ExpectationBuilder _ content: () -> (given: Given, when: When, then: Then)) {
+    public func expect(@ExpectationBuilder _ content: @escaping () -> (given: Given, when: When, then: Then)) {
 
         XCTContext.runActivity(named: content().given.title ) { _ in
             content().given.execute()
@@ -65,19 +65,23 @@ extension XCTestCase: Expecting {
             content().when.execute()
         }
 
-        XCTContext.runActivity(named: content().then.title ) { _ in
-            content().then.assert()
+        _ = XCTContext.runActivity(named: content().then.title ) { _ in
+            Task {
+                try await content().then.assert()
+            }
         }
     }
 
-    public func expect(@ExpectationBuilder _ content: () -> (when: When, then: Then)) {
+    public func expect(@ExpectationBuilder _ content: @escaping () -> (when: When, then: Then)) {
 
         XCTContext.runActivity(named: content().when.title ) { _ in
             content().when.execute()
         }
 
-        XCTContext.runActivity(named: content().then.title ) { _ in
-            content().then.assert()
+        _ = XCTContext.runActivity(named: content().then.title ) { _ in
+            Task {
+                try await content().then.assert()
+            }
         }
     }
 
diff --git a/Tests/RorschachTests/AssertionTests.swift b/Tests/RorschachTests/AssertionTests.swift
new file mode 100644
index 0000000..6d20e91
--- /dev/null
+++ b/Tests/RorschachTests/AssertionTests.swift
@@ -0,0 +1,46 @@
+//
+//  AssertionTests.swift
+//
+//
+//  Created by Martin Kim Dung-Pham on 25.01.24.
+//
+
+import Foundation
+import XCTest
+
+@testable import Rorschach
+
+class AssertionTests: XCTestCase {
+
+    func testDefault() {
+        let expectation = expectation(description: "")
+
+        let sut = Assertion("abc") {
+            _ = ""
+            expectation.fulfill()
+        }
+
+        sut.assert()
+
+        wait(for: [expectation], timeout: 0.1)
+        XCTAssertEqual(sut.title, "abc")
+    }
+
+    func testThrowing() async throws {
+        let expectation = expectation(description: "")
+
+        let sut = Assertion("abc") {
+            _ = try JSONDecoder().decode([String: String].self, from: self.json)
+            expectation.fulfill()
+        }
+
+        try await sut.assert()
+
+        await fulfillment(of: [expectation])
+        XCTAssertEqual(sut.title, "abc")
+    }
+
+    private let json = """
+        {"a":"A"}
+        """.data(using: .utf8)!
+}