diff --git a/doctest.sh b/doctest.sh
index e496ebda..f51fad17 100755
--- a/doctest.sh
+++ b/doctest.sh
@@ -76,7 +76,8 @@ nfail=0
 
 cd tmp/doctest
 for file in */*.jou; do
-    # print file and line number, as in "doc/foo.md:123: "
+    # Print file and line number, as in "doc/foo.md:123: "
+    # Newline is deleted to avoid warning on NetBSD 9.3, see issue #500
     echo -n "$(basename "$(dirname "$file")" | tr -d '\n' | base64 -d):$(basename "$file" | cut -d'.' -f1): "
 
     cp "$file" test.jou