diff --git a/join.1 b/join.1
index 66d782f..1b15e7d 100644
--- a/join.1
+++ b/join.1
@@ -38,11 +38,11 @@ then the remaining fields from
 .Bl -tag -width Ds
 .It Fl 1 Ar field
 Join on the
-.Ar field Ns eth
+.Ar field Ns th
 field of file 1.
 .It Fl 2 Ar field
 Join on the
-.Ar field Ns eth
+.Ar field Ns th
 field of file 2.
 .It Fl a Ar fileno
 Print unpairable lines from file