diff --git a/includes/client/comments.php b/includes/client/comments.php
index 3d7d78b..8bf6558 100644
--- a/includes/client/comments.php
+++ b/includes/client/comments.php
@@ -5,6 +5,7 @@ require_once plugin_dir_path( __FILE__ ) . '../server/activities/create.php';
 require_once plugin_dir_path( __FILE__ ) . '../server/activities/update.php';
 require_once plugin_dir_path( __FILE__ ) . '../server/activities/delete.php';
 require_once plugin_dir_path( __FILE__ ) . '../server/objects.php';
+require_once plugin_dir_path( __FILE__ ) . '../commentlinks.php';
 
 function handle_comment_post( $comment_id, $comment_approved ) {
     if ( $comment_approved ) {
@@ -21,10 +22,7 @@ function handle_edit_comment( $comment_id ) {
 }
 
 function handle_transition_comment_status( $new_status, $old_status, $comment ) {
-    global $wpdb;
-    $existing = $wpdb->get_row( $wpdb->prepare(
-        "SELECT * FROM {$wpdb->prefix}pterotype_comments WHERE comment_id = %d", $comment->comment_ID
-    ) );
+    $existing = \pterotype\commentlinks\get_object_id( $comment->comment_ID );
     if ( $existing ) {
         return;
     }
@@ -98,7 +96,6 @@ function get_comment_email_actor_slug( $comment ) {
 }
 
 function comment_to_object( $comment, $actor_slug ) {
-    global $wpdb;
     $post = \get_post( $comment->comment_post_ID );
     \setup_postdata( $post );
     $post_permalink = \get_permalink( $post );
@@ -106,15 +103,9 @@ function comment_to_object( $comment, $actor_slug ) {
     $inReplyTo = $post_object['id'];
     if ( $comment->comment_parent !== '0' ) {
         $parent_comment = \get_comment( $comment->comment_parent );
-        $parent_object_activitypub_id = $wpdb->get_var( $wpdb->prepare(
-            "
-           SELECT activitypub_id FROM {$wpdb->prefix}pterotype_comments
-           JOIN {$wpdb->prefix}pterotype_objects
-               ON {$wpdb->prefix}pterotype_comments.object_id = {$wpdb->prefix}pterotype_objects.id
-           WHERE comment_id = %d
-           ",
+        $parent_object_activitypub_id = \pterotype\commentlinks\get_object_activitypub_id(
             $parent_comment->comment_ID
-        ) );
+        );
         if ( $parent_object_activitypub_id ) {
             $inReplyTo = $parent_object_activitypub_id;
         }
@@ -130,16 +121,9 @@ function comment_to_object( $comment, $actor_slug ) {
         'url' => $link,
         'inReplyTo' => $inReplyTo,
     );
-    $existing_activitypub_id = $parent_object_activitypub_id = $wpdb->get_var( $wpdb->prepare(
-            "
-           SELECT activitypub_id FROM {$wpdb->prefix}pterotype_comments
-           JOIN {$wpdb->prefix}pterotype_objects
-               ON {$wpdb->prefix}pterotype_comments.object_id = {$wpdb->prefix}pterotype_objects.id
-           WHERE comment_id = %d
-           ",
-            $comment->comment_ID
-        ) );
-
+    $existing_activitypub_id = \pterotype\commentlinks\get_object_activitypub_id(
+        $comment->comment_ID
+    );
     if ( $existing_activitypub_id ) {
         $object['id'] = $existing_activitypub_id;
     }
diff --git a/includes/commentlinks.php b/includes/commentlinks.php
new file mode 100644
index 0000000..13d0721
--- /dev/null
+++ b/includes/commentlinks.php
@@ -0,0 +1,41 @@
+<?php
+namespace pterotype\commentlinks;
+
+function get_object_id( $comment_id ) {
+    global $wpdb;
+    return $wpdb->get_var( $wpdb->prepare(
+        "SELECT object_id FROM {$wpdb->prefix}pterotype_comments WHERE comment_id = %d",
+        $comment_id;
+    ) );
+}
+
+function get_comment_id( $object_id ) {
+    global $wpdb;
+    return $wpdb->get_var( $wpdb->prepare(
+        "SELECT comment_id FROM {$wpdb->prefix}pterotype_comments WHERE object_id = %d",
+        $object_id;
+    ) );
+}
+
+function get_object_activitypub_id( $comment_id ) {
+    global $wpdb;
+    return $wpdb->get_var( $wpdb->prepare(
+        "
+       SELECT activitypub_id FROM {$wpdb->prefix}pterotype_comments
+       JOIN {$wpdb->prefix}pterotype_objects
+         ON {$wpdb->prefix}pterotype_comments.object_id = {$wpdb->prefix}pterotype_objects.id
+       WHERE comment_id = %d
+       ",
+        $comment_id
+    ) );
+}
+
+function link_comment( $comment_id, $object_id ) {
+    global $wpdb;
+    return $wpdb->insert(
+        "{$wpdb->prefix}pterotype_comments",
+        array( 'comment_id' => $comment_id, 'object_id' => $object_id ),
+        '%d'
+    );
+}
+?>
diff --git a/includes/server/activities/create.php b/includes/server/activities/create.php
index 94ba5c8..4067eb9 100644
--- a/includes/server/activities/create.php
+++ b/includes/server/activities/create.php
@@ -4,6 +4,7 @@ namespace pterotype\activities\create;
 require_once plugin_dir_path( __FILE__ ) . '../objects.php';
 require_once plugin_dir_path( __FILE__ ) . '../actors.php';
 require_once plugin_dir_path( __FILE__ ) . '../../util.php';
+require_once plugin_dir_path( __FILE__ ) . '../../commentlinks.php';
 
 /*
 Create a new post or comment (depending on $activity["object"]["type"]),
@@ -108,7 +109,6 @@ function make_create( $actor_slug, $object ) {
 }
 
 function link_comment( $object ) {
-    global $wpdb;
     $object = \pterotype\util\dereference_object( $object );
     if ( ! array_key_exists( 'url', $object ) ) {
         return;
@@ -121,21 +121,13 @@ function link_comment( $object ) {
         return;
     }
     $object_id = \pterotype\objects\get_object_id( $object['id'] );
-    $wpdb->insert(
-        "{$wpdb->prefix}pterotype_comments",
-        array( 'comment_id' => $comment_id, 'object_id' => $object_id ),
-        '%d'
-    );
+    \pterotype\commentlinks\link_comment( $comment_id, $object_id );
 }
 
 function sync_comments( $activity ) {
-    global $wpdb;
     $object = $activity['object'];
     $object_id = \pterotype\objects\get_object_id( $object['id'] );
-    $comment_exists = $wpdb->get_row( $wpdb->prepare(
-        "SELECT * FROM {$wpdb->prefix}pterotype_comments WHERE object_id = %d",
-        $object_id
-    ) );
+    $comment_exists = \pterotype\commentlinks\get_comment_id( $object_id );
     if ( $comment_exists ) {
         return;
     }
@@ -151,10 +143,7 @@ function sync_comments( $activity ) {
     if ( ! $parent_row || is_wp_error( $parent_row ) ) {
         return;
     }
-    $parent_comment_id = $wpdb->get_var( $wpdb->prepare(
-        "SELECT comment_id FROM {$wpdb->prefix}pterotype_comments WHERE object_id = %d",
-        $parent_row->id
-    ) );
+    $parent_comment_id = \pterotype\commentlinks\get_comment_id( $parent_row->id );
     if ( $parent_comment_id ) {
         $parent_comment = \get_comment( $parent_comment_id );
         if ( ! $parent_comment ) {
@@ -181,12 +170,7 @@ function sync_comments( $activity ) {
 }
 
 function link_new_comment( $comment_id, $object_id ) {
-    global $wpdb;
-    return $wpdb->insert(
-        "{$wpdb->prefix}pterotype_comments",
-        array( 'comment_id' => $comment_id, 'object_id' => $object_id ),
-        '%d'
-    );
+    return \pterotype\commentlinks\link_comment( $comment_id, $object_id );
 }
 
 function get_comment_id_from_url( $url ) {