diff --git a/15_HInfinity_Filters.ipynb b/15_HInfinity_Filters.ipynb
index 8beb956..af58d5c 100644
--- a/15_HInfinity_Filters.ipynb
+++ b/15_HInfinity_Filters.ipynb
@@ -11,7 +11,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "# $H_\\infty$ filter"
+    "# H Infinity filter"
    ]
   },
   {
@@ -787,7 +787,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.4.2"
+   "version": "3.4.3"
   }
  },
  "nbformat": 4,