 
     /// Path of the `swift` interpreter.
     public var swiftInterpreter: AbsolutePath {
-        return swiftCompiler.parentDirectory.appending(component: "swift")
+        return swiftCompiler.parentDirectory.appending(component: "swift" + hostExecutableSuffix)
     }
 
     /// Path to the xctest utility.

        self.swiftCompiler = swiftCompilers.compile

        // Look for llbuild in bin dir.
        llbuild = binDir.appending(component: "swift-build-tool")
        guard localFileSystem.exists(llbuild) else {
            throw InvalidToolchainDiagnostic("could not find `llbuild` at expected path \(llbuild)")
        }

        func validateCompiler(at path: AbsolutePath?) throws {
            guard let path = path else { return }
            guard localFileSystem.isExecutableFile(path) else {
                throw InvalidToolchainDiagnostic("could not find the `swiftc\(hostExecutableSuffix)` at expected path \(path)")
            }
        }

