diff --git a/01-g-h-filter.ipynb b/01-g-h-filter.ipynb
index ee5225de..56345dea 100644
--- a/01-g-h-filter.ipynb
+++ b/01-g-h-filter.ipynb
@@ -1266,7 +1266,6 @@
     "    zs = []\n",
     "    for i in range(count):\n",
     "        zs.append(x0 + accel * (i**2) / 2 + dx*i + randn()*noise_factor)\n",
-    "        dx += accel\n",
     "    return zs\n",
     "   \n",
     "predictions = []\n",
@@ -2073,7 +2072,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.9.7"
+   "version": "3.10.4"
   },
   "nbdime-conflicts": {
    "local_diff": [