diff --git a/includes/class-signature.php b/includes/class-signature.php
index 96845d4..17a9a6f 100644
--- a/includes/class-signature.php
+++ b/includes/class-signature.php
@@ -225,7 +225,7 @@ class Signature {
 	public static function get_key( $keyId ) { // phpcs:ignore
 		// If there was no key passed to verify, it will find the keyId and call this
 		// function to fetch the public key from stored data or a network fetch.
-		$actor = \strip_fragment_from_url( $keyId ); // phpcs:ignore
+		$actor = \Activitypub\get_actor_from_key( $keyId ); // phpcs:ignore
 		$publicKeyPem = \Activitypub\get_publickey_by_actor( $actor, $keyId ); // phpcs:ignore
 		return \rtrim( $publicKeyPem ); // phpcs:ignore
 	}
diff --git a/includes/functions.php b/includes/functions.php
index 8f2e5d9..f731190 100644
--- a/includes/functions.php
+++ b/includes/functions.php
@@ -219,6 +219,15 @@ function get_publickey_by_actor( $actor, $key_id ) {
 	return new \WP_Error( 'activitypub_no_public_key', \__( 'No "Public-Key" found', 'activitypub' ), $metadata );
 }
 
+function get_actor_from_key( $key_id ) {
+	$actor = \strip_fragment_from_url( $key_id );
+ 	if ( $actor === $key_id ) {
+		// strip /main-key/ for GoToSocial.
+		$actor = \dirname( $key_id, 1 );
+	}
+	return $actor;
+}
+
 function get_follower_inboxes( $user_id ) {
 	$followers = \Activitypub\Peer\Followers::get_followers( $user_id );
 	$inboxes = array();