diff --git a/book/tools/opsin_api.md b/book/tools/opsin_api.md
index 2f7570c3..e0064ed6 100644
--- a/book/tools/opsin_api.md
+++ b/book/tools/opsin_api.md
@@ -36,7 +36,7 @@ add updates as he can, based on user issues/requests.
 OPSIN can be used by humans via the homepage where a single input box allows you to enter a valid IUPAC name (see figure below).  If you
 don't have an IUPAC name, and you don't have time to learn all the naming rules, the site will return an error with 
 information that the algorithm could not interpret.  While this might seem like a big negative for the site, it can
-be used to fix misspelling of systematic names amd it is really useful as a teaching tool where you give students a
+be used to fix misspelling of systematic names, and it is really useful as a teaching tool where you give students a
 structure and ask them to name it, checking the names with OPSIN.  For data science OPSIN also has an [API](https://opsin.ch.cam.ac.uk/instructions.html) and returns
 information back in JSON for easy use within scripting languages and other tools.