diff --git a/doc/src/sgml/install-windows.sgml b/doc/src/sgml/install-windows.sgml
index b33359d3af..30dd0c7f75 100644
--- a/doc/src/sgml/install-windows.sgml
+++ b/doc/src/sgml/install-windows.sgml
@@ -517,6 +517,40 @@ $ENV{PROVE_FLAGS}='--timer --jobs 2'
 $ENV{PROVE_TESTS}='t/020*.pl t/010*.pl'
 </programlisting>
   </para>
+
+  <para>
+   Some of the TAP tests depend on a set of external commands that would
+   optionally trigger tests related to them. Each one of those variables
+   can be set or unset in <filename>buildenv.pl</filename>:
+   <variablelist>
+    <varlistentry>
+     <term><varname>GZIP_PROGRAM</varname></term>
+     <listitem><para>
+       Path to a <application>gzip</application> command. The default is
+       <literal>gzip</literal>, that would be the command found in
+      <varname>PATH</varname>.
+     </para></listitem>
+    </varlistentry>
+
+    <varlistentry>
+     <term><varname>LZ4</varname></term>
+     <listitem><para>
+      Path to a <application>lz4</application> command. The default is
+      <literal>lz4</literal>, that would be the command found in
+      <varname>PATH</varname>.
+     </para></listitem>
+    </varlistentry>
+
+    <varlistentry>
+     <term><varname>TAR</varname></term>
+     <listitem><para>
+      Path to a <application>tar</application> command. The default is
+      <literal>tar</literal>, that would be the command found in
+      <varname>PATH</varname>.
+     </para></listitem>
+    </varlistentry>
+   </variablelist>
+  </para>
  </sect2>
 
  </sect1>
diff --git a/src/tools/msvc/vcregress.pl b/src/tools/msvc/vcregress.pl
index 5975e7c9cd..8775da4edf 100644
--- a/src/tools/msvc/vcregress.pl
+++ b/src/tools/msvc/vcregress.pl
@@ -30,6 +30,13 @@ my $tmp_installdir = "$topdir/tmp_install";
 do './src/tools/msvc/config_default.pl';
 do './src/tools/msvc/config.pl' if (-f 'src/tools/msvc/config.pl');
 
+# These values are defaults that can be overridden by the calling environment
+# (see buildenv.pl processing below).
+# c.f. src/Makefile.global.in and configure.ac
+$ENV{TAR} ||= 'tar';
+$ENV{LZ4} ||= 'lz4';
+$ENV{GZIP_PROGRAM} ||= 'gzip';
+
 # buildenv.pl is for specifying the build environment settings
 # it should contain lines like:
 # $ENV{PATH} = "c:/path/to/bison/bin;$ENV{PATH}";
@@ -67,13 +74,6 @@ $ENV{with_gssapi} = $config->{gss} ? 'yes' : 'no';
 $ENV{with_krb_srvnam} = $config->{krb_srvnam} || 'postgres';
 $ENV{with_readline} = 'no';
 
-# These values are defaults that can be overridden by the calling environment
-# (see buildenv.pl processing above).
-# c.f. src/Makefile.global.in and configure.ac
-$ENV{TAR} ||= 'tar';
-$ENV{LZ4} ||= 'lz4';
-$ENV{GZIP_PROGRAM} ||= 'gzip';
-
 $ENV{PATH} = "$topdir/$Config/libpq;$ENV{PATH}";
 
 if ($ENV{PERL5LIB})