diff --git a/man/rules/meson.build b/man/rules/meson.build
index 48da2f8f8c..b1d1c5d595 100644
--- a/man/rules/meson.build
+++ b/man/rules/meson.build
@@ -137,6 +137,7 @@ manpages = [
    'sd_id128_in_setv',
    'sd_id128_is_allf',
    'sd_id128_is_null',
+   'sd_id128_string_equal',
    'sd_id128_t'],
   ''],
  ['sd-journal', '3', [], ''],
diff --git a/man/sd-id128.xml b/man/sd-id128.xml
index 566cc2b595..c869943ad7 100644
--- a/man/sd-id128.xml
+++ b/man/sd-id128.xml
@@ -28,6 +28,7 @@
     <refname>SD_ID128_NULL</refname>
     <refname>SD_ID128_UUID_FORMAT_STR</refname>
     <refname>sd_id128_equal</refname>
+    <refname>sd_id128_string_equal</refname>
     <refname>sd_id128_in_set</refname>
     <refname>sd_id128_in_set_sentinel</refname>
     <refname>sd_id128_in_setv</refname>
@@ -75,6 +76,12 @@
         <paramdef>sd_id128_t <parameter>b</parameter></paramdef>
       </funcprototype>
 
+      <funcprototype>
+        <funcdef>int <function>sd_id128_string_equal</function></funcdef>
+        <paramdef>const char *<parameter>a</parameter></paramdef>
+        <paramdef>sd_id128_t <parameter>b</parameter></paramdef>
+      </funcprototype>
+
       <funcprototype>
         <funcdef>int <function>sd_id128_is_null</function></funcdef>
         <paramdef>sd_id128_t <parameter>id</parameter></paramdef>
@@ -200,6 +207,10 @@ int main(int argc, char **argv) {
   return 0;
 }</programlisting>
 
+    <para><function>sd_id128_string_equal()</function> is similar to <function>sd_id128_equal()</function>,
+    but the first ID is formatted as <type>const char*</type>. The same restrictions apply as to the first
+    argument of <function>sd_id128_from_string()</function>.</para>
+
     <para><function>sd_id128_is_null()</function> checks if an ID consists of only <constant>NUL</constant>
     bytes:</para>