diff --git a/doc/src/sgml/extend.sgml b/doc/src/sgml/extend.sgml
index ec95b4eb01..1a4f208692 100644
--- a/doc/src/sgml/extend.sgml
+++ b/doc/src/sgml/extend.sgml
@@ -1672,6 +1672,16 @@ include $(PGXS)
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><varname>NO_INSTALL</varname></term>
+      <listitem>
+       <para>
+        don't define an <literal>install</literal> target, useful for test
+        modules that don't need their build products to be installed.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><varname>NO_INSTALLCHECK</varname></term>
       <listitem>
diff --git a/src/makefiles/pgxs.mk b/src/makefiles/pgxs.mk
index 271e7eaba8..224eac069c 100644
--- a/src/makefiles/pgxs.mk
+++ b/src/makefiles/pgxs.mk
@@ -49,6 +49,8 @@
 #   TAP_TESTS -- switch to enable TAP tests
 #   ISOLATION -- list of isolation test cases
 #   ISOLATION_OPTS -- additional switches to pass to pg_isolation_regress
+#   NO_INSTALL -- don't define an install target, useful for test modules
+#     that don't need their build products to be installed
 #   NO_INSTALLCHECK -- don't define an installcheck target, useful e.g. if
 #     tests require special configuration, or don't use pg_regress
 #   EXTRA_CLEAN -- extra files to remove in 'make clean'