diff --git a/Package@swift-4.2.swift b/Package@swift-4.2.swift
new file mode 100644
index 0000000..7208ddb
--- /dev/null
+++ b/Package@swift-4.2.swift
@@ -0,0 +1,16 @@
+// swift-tools-version:4.2
+
+import PackageDescription
+
+
+let package = Package(
+  name: "Spectre",
+  products: [
+    .library(name: "Spectre", targets: ["Spectre"]),
+  ],
+  targets: [
+    .target(name: "Spectre", dependencies: []),
+    .testTarget(name: "SpectreTests", dependencies: ["Spectre"]),
+  ],
+  swiftLanguageVersions: [.v4, .v4_2]
+)
diff --git a/Sources/Spectre/Expectation.swift b/Sources/Spectre/Expectation.swift
index d450839..b3cd900 100644
--- a/Sources/Spectre/Expectation.swift
+++ b/Sources/Spectre/Expectation.swift
@@ -22,7 +22,7 @@ struct ExpectationFailure : FailureType {
 
 open class Expectation<T> : ExpectationType {
   public typealias ValueType = T
-  open let expression: () throws -> ValueType?
+  public let expression: () throws -> ValueType?
 
   let file: String
   let line: Int