diff --git a/notebooks/manual/ExternalFunctions.ipynb b/notebooks/manual/ExternalFunctions.ipynb
index 2c450d9100c1f18fff60f84098234b903b636f4e..61042fbdfd88bc454a3aff8a31ed8329aa0dd4cc 100644
--- a/notebooks/manual/ExternalFunctions.ipynb
+++ b/notebooks/manual/ExternalFunctions.ipynb
@@ -1288,9 +1288,9 @@
    "source": [
     "### FORMAT_TO_STRING\n",
     "This external function takes a format string and a B sequence of values and generates an output string, where the values have been inserted into the format string in place of the `~w` placeholders.\n",
-    " - the length of sequence must correspond to the number of \\verb+~w+ in the format string.\n",
+    " - the length of sequence must correspond to the number of `~w` in the format string.\n",
     " - the format string follows the conventions of SICStus Prolog.\n",
-    "    E.g., one can use \\verb+~n+ for newlines.\n",
+    "    E.g., one can use `~n` for newlines.\n",
     "\n",
     "\n",
     "Type: $(STRING*seq(\\tau)) \\rightarrow STRING$."