diff --git a/Makefile b/Makefile
index 765f997..e1e0973 100644
--- a/Makefile
+++ b/Makefile
@@ -135,7 +135,7 @@ check: $(TEST_TARGETS)
 .PHONY: spell
 # npm install -g cspell; add exceptions to cSpell.json
 spell:
-	cspell **/*.hh **/*.cc manual/* ChangeLog README* TODO
+	cspell **/*.hh include/qpdf/*.h **/*.cc manual/* ChangeLog README* TODO
 
 # Install targets are in the make directory in the rules-specific make
 # fragments.