     func testModuleValueReference() throws {
         try Device.current.sync {
             let source =
-                "extern \"C\" __global__ void sum(float *x, int count, float *out) {"
+                "extern \"C\" __global__ void sum(const float *x, int count, float *out) {"
               + "    *out = 0; for (int i = 0; i < count; i++) *out += x[i]; "
               + "}"
 

            let module = try Module(ptx: ptx)
            let saxpy = module.function(named: "sum")!

            var x = DeviceArray<Float>(Array(sequence(first: 0, next: {$0+1}).prefix(512)))
            var out = DeviceValue<Float>()

            /// Launch kernel
            try saxpy<<<(1, 1)>>>[.array(&x), .int(Int32(x.count)), .value(&out)]

            XCTAssertEqual(out.value, 130816)
        }

    
    static var allTests : [(String, (WarpTests) -> () throws -> Void)] {
        return [
            ("testArray", testArray),
            ("testValue", testValue),
            ("testModuleMult", testModuleMult),
            ("testModuleSaxpy", testModuleSaxpy),
            ("testModuleValueReference", testModuleValueReference),
            ("testCollectionOperations", testCollectionOperations),
        ]
    }

