diff --git a/man3/strlen.3 b/man3/strlen.3
index dea4c1050..ca7a7d188 100644
--- a/man3/strlen.3
+++ b/man3/strlen.3
@@ -64,6 +64,11 @@ T}	Thread safety	MT-Safe
 .hy
 .ad
 .sp 1
+.SH NOTES
+In cases where the input buffer may not contain
+a terminating null byte,
+.BR strnlen (3)
+should be used instead.
 .SH CONFORMING TO
 POSIX.1-2001, POSIX.1-2008, C89, C99, C11, SVr4, 4.3BSD.
 .SH SEE ALSO
diff --git a/man3/wcslen.3 b/man3/wcslen.3
index af3fcb9ca..24dca8e55 100644
--- a/man3/wcslen.3
+++ b/man3/wcslen.3
@@ -56,6 +56,11 @@ T}	Thread safety	MT-Safe
 .hy
 .ad
 .sp 1
+.SH NOTES
+In cases where the input buffer may not contain
+a terminating null wide character,
+.BR wcsnlen (3)
+should be used instead.
 .SH CONFORMING TO
 POSIX.1-2001, POSIX.1-2008, C99.
 .SH SEE ALSO