diff --git a/source/iostreams.tex b/source/iostreams.tex
index 5eb66574a8..e1e57e5e5f 100644
--- a/source/iostreams.tex
+++ b/source/iostreams.tex
@@ -3939,7 +3939,7 @@
 The pending sequence is defined as the concatenation of
 \begin{itemize}
 \item
-the empty sequence if \tcode{pbase()} is not null, otherwise the
+the empty sequence if \tcode{pbase()} is null, otherwise the
 \tcode{pptr() - pbase()}
 characters beginning at
 \tcode{pbase()}, followed by