diff --git a/2.6_chiseltest.ipynb b/2.6_chiseltest.ipynb
index d4b4e7e..d00de66 100644
--- a/2.6_chiseltest.ipynb
+++ b/2.6_chiseltest.ipynb
@@ -420,26 +420,26 @@
     "  val x           = Reg(UInt())\n",
     "  val y           = Reg(UInt())\n",
     "  val busy        = RegInit(false.B)\n",
-    "  val resultValid = RegInit(false.B)\n",
     "\n",
     "  input.ready := ! busy\n",
-    "  output.valid := resultValid\n",
     "  output.bits := DontCare\n",
+    "  output.valid := false.B\n",
     "\n",
     "  when(busy)  {\n",
     "    // during computation keep subtracting the smaller from the larger\n",
-    "    when(x > y) {\n",
-    "      x := x - y\n",
+    "    when(y > 0.U) {\n",
+    "      when(x > y) {\n",
+    "        x := x - y\n",
+    "      }.otherwise {\n",
+    "        y := y - x\n",
+    "      }\n",
     "    }.otherwise {\n",
-    "      y := y - x\n",
-    "    }\n",
-    "    when(y === 0.U) {\n",
     "      // when y becomes zero computation is over, signal valid data to output\n",
     "      output.bits.value1 := xInitial\n",
     "      output.bits.value2 := yInitial\n",
     "      output.bits.gcd := x\n",
     "      output.valid := true.B\n",
-    "      busy := false.B\n",
+    "      busy := ! output.ready\n",
     "    }\n",
     "  }.otherwise {\n",
     "    when(input.valid) {\n",
@@ -450,7 +450,7 @@
     "      xInitial := bundle.value1\n",
     "      yInitial := bundle.value2\n",
     "      busy := true.B\n",
-    "      resultValid := false.B\n",
+    "      output.valid := false.B\n",
     "    }\n",
     "  }\n",
     "}\n"
@@ -483,9 +483,19 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "test(new DecoupledGcd(16)) { dut =>\n",
+    "\n",
+    "test(new MultiIOModule {\n",
+    "       val input = IO(Flipped(Decoupled(new GcdInputBundle(16))))\n",
+    "       val output = IO(Decoupled(new GcdOutputBundle(16)))\n",
+    "       val clk8to1 = IO(Output(Clock()))\n",
+    "       val gcd = Module(new DecoupledGcd(16))\n",
+    "       gcd.input := input\n",
+    "       output := gcd.output\n",
+    "       val cnt = Counter(true.B, 16)\n",
+    "       clk8to1 := cnt._1(3).asClock\n",
+    "}) { dut =>\n",
     "  dut.input.initSource().setSourceClock(dut.clock)\n",
-    "  dut.output.initSink().setSinkClock(dut.clock)\n",
+    "  dut.output.initSink().setSinkClock(dut.clk8to1)  // the sink uses a slower clock so that backpressure is more likely\n",
     "\n",
     "  val testValues = for { x <- 1 to 10; y <- 1 to 10} yield (x, y)\n",
     "  val inputSeq = testValues.map { case (x, y) =>\n",
@@ -500,7 +510,7 @@
     "  }.fork {\n",
     "    dut.output.expectDequeueSeq(resultSeq)\n",
     "  }.join()\n",
-    "}\n"
+    "}"
    ]
   },
   {
@@ -531,4 +541,4 @@
  },
  "nbformat": 4,
  "nbformat_minor": 2
-}
+}
\ No newline at end of file