+diff --git a/zdiff.1 b/zdiff.1
+index 588974c..3a586a2 100644
+--- a/zdiff.1
++++ b/zdiff.1
+@@ -10,6 +10,7 @@ zcmp, zdiff \- compare compressed files
+ [ diff_options ] file1
+ [ file2 ]
+ .SH DESCRIPTION
++.P
+ .I Zcmp
+ and
+ .I zdiff
+@@ -23,11 +24,11 @@ All options specified are passed directly to
+ .I cmp
+ or
+ .IR diff "."
+-If only 1 file is specified, then the files compared are
+-.I file1
+-and an uncompressed
+-.IR file1 ".gz."
+-If two files are specified, then they are uncompressed if necessary and fed to
++If only one file is specified, then it is compared to a file with the same name
++without the
++.I ".gz"
++extension. If two files are specified, then they are uncompressed if necessary
++and fed to
+ .I cmp
+ or
+ .IR diff "."
+@@ -36,6 +37,13 @@ The exit status from
+ or
+ .I diff
+ is preserved.
++.P
++When both files must be uncompressed before comparison, the second is
++uncompressed to
++.IR "/tmp" "."
++In all other cases,
++.IR "zdiff" " and " "zcmp"
++use only a pipe.
+ .SH "SEE ALSO"
+ cmp(1), diff(1), zmore(1), zgrep(1), znew(1), zforce(1), gzip(1), gzexe(1)
+ .SH BUGS