diff --git a/includes/class-signature.php b/includes/class-signature.php
index a56a206..1032438 100644
--- a/includes/class-signature.php
+++ b/includes/class-signature.php
@@ -1,6 +1,7 @@
 <?php
 namespace Activitypub;
 
+use WP_Error;
 use DateTime;
 use DateTimeZone;
 
@@ -142,7 +143,7 @@ class Signature {
 		}
 
 		if ( ! isset( $headers['signature'] ) ) {
-			return new \WP_Error( 'activitypub_signature', 'Request not signed', array( 'status' => 403 ) );
+			return new WP_Error( 'activitypub_signature', 'Request not signed', array( 'status' => 403 ) );
 		}
 
 		if ( array_key_exists( 'signature', $headers ) ) {
@@ -152,7 +153,7 @@ class Signature {
 		}
 
 		if ( ! isset( $signature_block ) || ! $signature_block ) {
-			return new \WP_Error( 'activitypub_signature', 'Incompatible request signature. keyId and signature are required', array( 'status' => 403 ) );
+			return new WP_Error( 'activitypub_signature', 'Incompatible request signature. keyId and signature are required', array( 'status' => 403 ) );
 		}
 
 		$signed_headers = $signature_block['headers'];
@@ -162,12 +163,12 @@ class Signature {
 
 		$signed_data = self::get_signed_data( $signed_headers, $signature_block, $headers );
 		if ( ! $signed_data ) {
-			return new \WP_Error( 'activitypub_signature', 'Signed request date outside acceptable time window', array( 'status' => 403 ) );
+			return new WP_Error( 'activitypub_signature', 'Signed request date outside acceptable time window', array( 'status' => 403 ) );
 		}
 
 		$algorithm = self::get_signature_algorithm( $signature_block );
 		if ( ! $algorithm ) {
-			return new \WP_Error( 'activitypub_signature', 'Unsupported signature algorithm (only rsa-sha256 and hs2019 are supported)', array( 'status' => 403 ) );
+			return new WP_Error( 'activitypub_signature', 'Unsupported signature algorithm (only rsa-sha256 and hs2019 are supported)', array( 'status' => 403 ) );
 		}
 
 		if ( \in_array( 'digest', $signed_headers, true ) && isset( $body ) ) {
@@ -183,7 +184,7 @@ class Signature {
 			}
 
 			if ( \base64_encode( \hash( $hashalg, $body, true ) ) !== $digest[1] ) { // phpcs:ignore
-				return new \WP_Error( 'activitypub_signature', 'Invalid Digest header', array( 'status' => 403 ) );
+				return new WP_Error( 'activitypub_signature', 'Invalid Digest header', array( 'status' => 403 ) );
 			}
 		}
 
@@ -193,7 +194,7 @@ class Signature {
 		}
 		$verified = \openssl_verify( $signed_data, $signature_block['signature'], $public_key, $algorithm ) > 0;
 		if ( ! $verified ) {
-			return new \WP_Error( 'activitypub_signature', 'Invalid signature', array( 'status' => 403 ) );
+			return new WP_Error( 'activitypub_signature', 'Invalid signature', array( 'status' => 403 ) );
 		}
 		return $verified;
 	}