diff --git a/examples/sample.ipynb b/examples/sample.ipynb
index 70ed68c..3612465 100644
--- a/examples/sample.ipynb
+++ b/examples/sample.ipynb
@@ -556,7 +556,7 @@
     "@spacy.registry.misc(\"prefix_scrubber\")\n",
     "def prefix_scrubber():\n",
     "\tdef scrubber_func(span: Span) -> str:\n",
-    "\t\twhile span[0].text in (\"a\", \"the\", \"their\", \"every\", \"other\"):\n",
+    "\t\twhile len(span) > 1 and span[0].text in (\"a\", \"the\", \"their\", \"every\", \"other\"):\n",
     "\t\t\tspan = span[1:]\n",
     "\t\treturn span.text\n",
     "\treturn scrubber_func\n",