diff --git a/lod/01_SPARQL_Introduction.ipynb b/lod/01_SPARQL_Introduction.ipynb
index bee235e..9da9404 100755
--- a/lod/01_SPARQL_Introduction.ipynb
+++ b/lod/01_SPARQL_Introduction.ipynb
@@ -1771,7 +1771,7 @@
     "In one of the exercises, we excluded lead and backing vocals from the list of instruments.\n",
     "However, are those the only types of vocals?\n",
     "\n",
-    "You can check if a string or URI matches a regular expression with `regex(?variable, \"<regex>\")`.\n",
+    "You can check if a string or URI matches a regular expression with `regex(?variable, \"<regex>\", \"i\")`.\n",
     "\n",
     "The documentation for regular expressions in SPARQL is [here](https://www.w3.org/TR/rdf-sparql-query/)."
    ]