diff --git a/5-UsefulConceptsAndSTL/1-ErrorHandling.ipynb b/5-UsefulConceptsAndSTL/1-ErrorHandling.ipynb
index 076b4c79c46a15e9d8e1b3a51b401de6c1aae71b..a3600d3597e84b7a25d56dc69b7a5789ece9f331 100644
--- a/5-UsefulConceptsAndSTL/1-ErrorHandling.ipynb
+++ b/5-UsefulConceptsAndSTL/1-ErrorHandling.ipynb
@@ -494,7 +494,7 @@
     "I don't like these error codes much, because:\n",
     "\n",
     "* The result can't be naturally given in return value and must be provided in argument.\n",
-    "* You have to bookkeep the possible error codes somewhere, and an user must know this somewhere to go consult them if something happens (usually a header file: see for instance one for [PETSc library](https://www.mcs.anl.gov/petsc/petsc-master/include/petscerror.h.html)).\n",
+    "* You have to bookkeep the possible error codes somewhere, and a user must know this somewhere to go consult them if something happens (usually a header file: see for instance one for [PETSc library](https://www.mcs.anl.gov/petsc/petsc-master/include/petscerror.h.html)).\n",
     "* In the libraries that use them, more often than not some are not self descriptive and you have to figure out what the hell the issue is.\n",
     "* And more importantly, this relies on the end-user thinking to check the error value:"
    ]