diff --git a/TODO.md b/TODO.md
index 4a6ac8a..877c45e 100644
--- a/TODO.md
+++ b/TODO.md
@@ -533,7 +533,7 @@ so, I find it useful to make reference to them in this list.
 * Look at places in the code where object traversal is being done and, where possible, try to avoid
   it entirely or at least avoid ever traversing the same objects multiple times.
 
-* The CLI warants a thorough review, including the introduction of proper sub-commands. Add warnings
+* The CLI warrants a thorough review, including the introduction of proper sub-commands. Add warnings
   for file names without extension or path element as first parameter
   (see https://github.com/qpdf/qpdf/pull/1381).
 
diff --git a/cSpell.json b/cSpell.json
index 2122d85..2e10fe7 100644
--- a/cSpell.json
+++ b/cSpell.json
@@ -690,6 +690,7 @@
     "unversioned",
     "upages",
     "upass",
+    "upcasting",
     "urandom",
     "userpasswordmatched",
     "uval",
diff --git a/manual/release-notes.rst b/manual/release-notes.rst
index 63b90aa..117318b 100644
--- a/manual/release-notes.rst
+++ b/manual/release-notes.rst
@@ -15,6 +15,8 @@ more detail.
 
 .. _r12-0-0:
 
+.. cSpell:ignore substract
+
 12.0.0: not yet released
   - API: breaking changes