diff --git a/doc/arm/Bv9ARM.ch06.html b/doc/arm/Bv9ARM.ch06.html
index 2978764b77..b58c60d0c5 100644
--- a/doc/arm/Bv9ARM.ch06.html
+++ b/doc/arm/Bv9ARM.ch06.html
@@ -6096,16 +6096,24 @@ avoid-v6-udp-ports { 40000; range 50000 60000; };
 <dt><span class="term"><span class="command"><strong>max-journal-size</strong></span></span></dt>
 <dd>
                 <p>
-                  Sets a maximum size for each journal file
-                  (see <a class="xref" href="Bv9ARM.ch04.html#journal" title="The journal file">the section called &#8220;The journal file&#8221;</a>).  When the journal file
-                  approaches
-                  the specified size, some of the oldest transactions in the
-                  journal
-                  will be automatically removed.  The largest permitted
-                  value is 2 gigabytes. The default is
-                  <code class="literal">unlimited</code>, which also
-                  means 2 gigabytes.
-                  This may also be set on a per-zone basis.
+                  Sets a maximum size for each journal file (see
+                  <a class="xref" href="Bv9ARM.ch04.html#journal" title="The journal file">the section called &#8220;The journal file&#8221;</a>), expressed in bytes
+                  or, if followed by an optional unit suffix ('k',
+                  'm', or 'g'), in kilobytes, megabytes, or gigabytes.
+                  When the journal file approaches the specified size,
+                  some of the oldest transactions in the journal
+                  will be automatically removed. The largest
+                  permitted value is 2 gigabytes.  Very small
+                  values are rounded up to 4096 bytes.  You
+                  can specify <code class="literal">unlimited</code>, which
+                  also means 2 gigabytes. If you set the limit to
+                  <code class="literal">default</code> or leave it unset, the
+                  journal is allowed to grow up to twice as large as
+                  the zone. (There is little benefit in storing
+                  larger journals.)
+                </p>
+                <p>
+                  This option may also be set on a per-zone basis.
                 </p>
               </dd>
 <dt><span class="term"><span class="command"><strong>max-records</strong></span></span></dt>
diff --git a/doc/arm/Bv9ARM.ch09.html b/doc/arm/Bv9ARM.ch09.html
index 66fda306fa..38453a39c5 100644
--- a/doc/arm/Bv9ARM.ch09.html
+++ b/doc/arm/Bv9ARM.ch09.html
@@ -197,6 +197,16 @@
 <div class="titlepage"><div><div><h3 class="title">
 <a name="relnotes_features"></a>New Features</h3></div></div></div>
     <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
+<li class="listitem">
+	<p>
+	  Setting <span class="command"><strong>max-journal-size</strong></span> to
+	  <code class="literal">default</code> limits journal sizes to twice the
+	  size of the zone contents.  This can be overridden by setting
+	  <span class="command"><strong>max-journal-size</strong></span> to <code class="literal">unlimited</code>
+	  or to an explicit value up to 2G. Thanks to Tony Finch for
+	  the contribution. [RT #38324]
+	</p>
+      </li>
 <li class="listitem">
         <p>
 	  The <span class="command"><strong>new-zones-directory</strong></span> option allows
diff --git a/doc/arm/notes.html b/doc/arm/notes.html
index a0151616a2..3803961e23 100644
--- a/doc/arm/notes.html
+++ b/doc/arm/notes.html
@@ -160,6 +160,16 @@
 <div class="titlepage"><div><div><h3 class="title">
 <a name="relnotes_features"></a>New Features</h3></div></div></div>
     <div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
+<li class="listitem">
+	<p>
+	  Setting <span class="command"><strong>max-journal-size</strong></span> to
+	  <code class="literal">default</code> limits journal sizes to twice the
+	  size of the zone contents.  This can be overridden by setting
+	  <span class="command"><strong>max-journal-size</strong></span> to <code class="literal">unlimited</code>
+	  or to an explicit value up to 2G. Thanks to Tony Finch for
+	  the contribution. [RT #38324]
+	</p>
+      </li>
 <li class="listitem">
         <p>
 	  The <span class="command"><strong>new-zones-directory</strong></span> option allows
diff --git a/doc/misc/options b/doc/misc/options
index da8fbf1e14..f8002dbcff 100644
--- a/doc/misc/options
+++ b/doc/misc/options
@@ -219,7 +219,7 @@ options {
         max-cache-ttl <integer>;
         max-clients-per-query <integer>;
         max-ixfr-log-size ( default | unlimited | <sizeval> ); // obsolete
-        max-journal-size ( unlimited | <sizeval> );
+        max-journal-size ( default | unlimited | <sizeval> );
         max-ncache-ttl <integer>;
         max-records <integer>;
         max-recursion-depth <integer>;
@@ -543,7 +543,7 @@ view <string> [ <class> ] {
         max-cache-ttl <integer>;
         max-clients-per-query <integer>;
         max-ixfr-log-size ( default | unlimited | <sizeval> ); // obsolete
-        max-journal-size ( unlimited | <sizeval> );
+        max-journal-size ( default | unlimited | <sizeval> );
         max-ncache-ttl <integer>;
         max-records <integer>;
         max-recursion-depth <integer>;
@@ -743,7 +743,7 @@ view <string> [ <class> ] {
                     port <integer> ] ) [ key <string> ]; ... };
                 max-ixfr-log-size ( default | unlimited |
                     <sizeval> ); // obsolete
-                max-journal-size ( unlimited | <sizeval> );
+                max-journal-size ( default | unlimited | <sizeval> );
                 max-records <integer>;
                 max-refresh-time <integer>;
                 max-retry-time <integer>;
@@ -847,7 +847,7 @@ zone <string> [ <class> ] {
             <ipv4_address> [ port <integer> ] | <ipv6_address> [ port
             <integer> ] ) [ key <string> ]; ... };
         max-ixfr-log-size ( default | unlimited | <sizeval> ); // obsolete
-        max-journal-size ( unlimited | <sizeval> );
+        max-journal-size ( default | unlimited | <sizeval> );
         max-records <integer>;
         max-refresh-time <integer>;
         max-retry-time <integer>;