diff --git a/reference/pcre/constants.xml b/reference/pcre/constants.xml
index d3759e4a977b..269814f3a57c 100644
--- a/reference/pcre/constants.xml
+++ b/reference/pcre/constants.xml
@@ -94,8 +94,10 @@
      <entry>
       This flag tells <function>preg_match</function> and
       <function>preg_match_all</function> to include unmatched subpatterns in
-      <varname>$matches</varname> as &null; values. Without this flag, unmatched
-      subpatterns are reported as empty strings, as if they were empty matches.
+      <varname>$matches</varname> as &null; values, including trailing
+      unmatched subpatterns. Without this flag, non-trailing unmatched
+      subpatterns are reported as empty strings, while trailing unmatched
+      subpatterns are omitted from the results entirely.
       Setting this flag allows to distinguish between these two cases.
      </entry>
      <entry>7.2.0</entry>
diff --git a/reference/pcre/functions/preg-match-all.xml b/reference/pcre/functions/preg-match-all.xml
index d5387b6952f1..54ba7af38125 100644
--- a/reference/pcre/functions/preg-match-all.xml
+++ b/reference/pcre/functions/preg-match-all.xml
@@ -242,10 +242,14 @@ Array
         <varlistentry>
          <term><constant>PREG_UNMATCHED_AS_NULL</constant></term>
          <listitem>
-          <para>
-           If this flag is passed, unmatched subpatterns are reported as &null;;
-           otherwise they are reported as an empty <type>string</type>.
-          </para>
+          <simpara>
+           If this flag is passed, unmatched subpatterns are reported as &null;
+           and are always included in the results (including trailing ones).
+           Without this flag, unmatched subpatterns that are followed by a
+           matched subpattern are reported as an empty <type>string</type>,
+           while trailing unmatched subpatterns are omitted from the results
+           entirely.
+          </simpara>
          </listitem>
         </varlistentry>  
        </variablelist>
@@ -301,6 +305,14 @@ Array
       </row>
      </thead>
      <tbody>
+      <row>
+       <entry>7.4.0</entry>
+       <entry>
+        When the <constant>PREG_UNMATCHED_AS_NULL</constant> flag is used,
+        trailing unmatched capturing groups are now also included in the
+        result with the value &null;. Previously, they were omitted.
+       </entry>
+      </row>
       <row>
        <entry>7.2.0</entry>
        <entry>
diff --git a/reference/pcre/functions/preg-match.xml b/reference/pcre/functions/preg-match.xml
index 11587ac3144e..93f23f48d2a9 100644
--- a/reference/pcre/functions/preg-match.xml
+++ b/reference/pcre/functions/preg-match.xml
@@ -119,8 +119,12 @@ Array
          <term><constant>PREG_UNMATCHED_AS_NULL</constant></term>
          <listitem>
           <para>
-           If this flag is passed, unmatched subpatterns are reported as &null;;
-           otherwise they are reported as an empty <type>string</type>.
+           If this flag is passed, unmatched subpatterns are reported as &null;
+           and are always included in the results (including trailing ones).
+           Without this flag, unmatched subpatterns that are followed by a
+           matched subpattern are reported as an empty <type>string</type>,
+           while trailing unmatched subpatterns are omitted from the results
+           entirely.
            <informalexample>
             <programlisting role="php">
 <![CDATA[
@@ -129,6 +133,12 @@ preg_match('/(a)(b)*(c)/', 'ac', $matches);
 var_dump($matches);
 preg_match('/(a)(b)*(c)/', 'ac', $matches, PREG_UNMATCHED_AS_NULL);
 var_dump($matches);
+
+// Trailing unmatched subpatterns:
+preg_match('/(a)(b)?(c)?/', 'a', $matches);
+var_dump($matches);
+preg_match('/(a)(b)?(c)?/', 'a', $matches, PREG_UNMATCHED_AS_NULL);
+var_dump($matches);
 ?>
 ]]>
             </programlisting>
@@ -155,6 +165,22 @@ array(4) {
   [3]=>
   string(1) "c"
 }
+array(2) {
+  [0]=>
+  string(1) "a"
+  [1]=>
+  string(1) "a"
+}
+array(4) {
+  [0]=>
+  string(1) "a"
+  [1]=>
+  string(1) "a"
+  [2]=>
+  NULL
+  [3]=>
+  NULL
+}
 ]]>
             </screen>
            </informalexample>
@@ -270,6 +296,14 @@ Array
       </row>
      </thead>
      <tbody>
+      <row>
+       <entry>7.4.0</entry>
+       <entry>
+        When the <constant>PREG_UNMATCHED_AS_NULL</constant> flag is used,
+        trailing unmatched capturing groups are now also included in the
+        result with the value &null;. Previously, they were omitted.
+       </entry>
+      </row>
       <row>
        <entry>7.2.0</entry>
        <entry>