diff --git a/doc/src/sgml/ref/copy.sgml b/doc/src/sgml/ref/copy.sgml
index 5be3514..13cd528 100644
--- a/doc/src/sgml/ref/copy.sgml
+++ b/doc/src/sgml/ref/copy.sgml
@@ -477,6 +477,13 @@ COPY <replaceable class="parameter">count</replaceable>
     <command>VACUUM</command> to recover the wasted space.
    </para>
 
+   <para>
+    <literal>FORCE_NULL</> and <literal>FORCE_NOT_NULL</> can be used
+    simultaneously on the same column. This has as result to convert quoted
+    null strings to null values and to convert unquoted null strings to
+    empty strings.
+   </para>
+
  </refsect1>
 
  <refsect1>
diff --git a/src/test/regress/expected/copy2.out b/src/test/regress/expected/copy2.out
index 76dea28..035d843 100644
--- a/src/test/regress/expected/copy2.out
+++ b/src/test/regress/expected/copy2.out
@@ -383,7 +383,6 @@ SELECT * FROM vistest;
 (2 rows)
 
 -- Test FORCE_NOT_NULL and FORCE_NULL options
--- should succeed with "b" set to an empty string and "c" set to NULL
 CREATE TEMP TABLE forcetest (
     a INT NOT NULL,
     b TEXT NOT NULL,
@@ -392,6 +391,7 @@ CREATE TEMP TABLE forcetest (
     e TEXT
 );
 \pset null NULL
+-- should succeed with no effect ("b" remains an empty string, "c" remains NULL)
 BEGIN;
 COPY forcetest (a, b, c) FROM STDIN WITH (FORMAT csv, FORCE_NOT_NULL(b), FORCE_NULL(c));
 COMMIT;
@@ -401,12 +401,12 @@ SELECT b, c FROM forcetest WHERE a = 1;
    | NULL
 (1 row)
 
--- should succeed with no effect ("b" remains an empty string, "c" remains NULL)
+-- should succeed, FORCE_NULL and FORCE_NOT_NULL can be both specified
 BEGIN;
-COPY forcetest (a, b, c) FROM STDIN WITH (FORMAT csv, FORCE_NOT_NULL(b), FORCE_NULL(c));
+COPY forcetest (a, b, c, d) FROM STDIN WITH (FORMAT csv, FORCE_NOT_NULL(c,d), FORCE_NULL(c,d));
 COMMIT;
-SELECT b, c FROM forcetest WHERE a = 2;
- b |  c   
+SELECT c, d FROM forcetest WHERE a = 2;
+ c |  d   
 ---+------
    | NULL
 (1 row)
diff --git a/src/test/regress/sql/copy2.sql b/src/test/regress/sql/copy2.sql
index e2be21f..248055f 100644
--- a/src/test/regress/sql/copy2.sql
+++ b/src/test/regress/sql/copy2.sql
@@ -271,7 +271,6 @@ SELECT * FROM vistest;
 COMMIT;
 SELECT * FROM vistest;
 -- Test FORCE_NOT_NULL and FORCE_NULL options
--- should succeed with "b" set to an empty string and "c" set to NULL
 CREATE TEMP TABLE forcetest (
     a INT NOT NULL,
     b TEXT NOT NULL,
@@ -280,19 +279,20 @@ CREATE TEMP TABLE forcetest (
     e TEXT
 );
 \pset null NULL
+-- should succeed with no effect ("b" remains an empty string, "c" remains NULL)
 BEGIN;
 COPY forcetest (a, b, c) FROM STDIN WITH (FORMAT csv, FORCE_NOT_NULL(b), FORCE_NULL(c));
 1,,""
 \.
 COMMIT;
 SELECT b, c FROM forcetest WHERE a = 1;
--- should succeed with no effect ("b" remains an empty string, "c" remains NULL)
+-- should succeed, FORCE_NULL and FORCE_NOT_NULL can be both specified
 BEGIN;
-COPY forcetest (a, b, c) FROM STDIN WITH (FORMAT csv, FORCE_NOT_NULL(b), FORCE_NULL(c));
-2,,""
+COPY forcetest (a, b, c, d) FROM STDIN WITH (FORMAT csv, FORCE_NOT_NULL(c,d), FORCE_NULL(c,d));
+2,'a',,""
 \.
 COMMIT;
-SELECT b, c FROM forcetest WHERE a = 2;
+SELECT c, d FROM forcetest WHERE a = 2;
 -- should fail with not-null constraint violation
 BEGIN;
 COPY forcetest (a, b, c) FROM STDIN WITH (FORMAT csv, FORCE_NULL(b), FORCE_NOT_NULL(c));