Index: src/wp-includes/class-wp-image-editor-imagick.php
===================================================================
--- src/wp-includes/class-wp-image-editor-imagick.php	(revision 36763)
+++ src/wp-includes/class-wp-image-editor-imagick.php	(working copy)
@@ -83,8 +83,9 @@
 		if ( ! ( defined( 'imagick::COMPRESSION_JPEG' ) && defined( 'imagick::FILTER_TRIANGLE' ) ) )
 			return false;
 
-		if ( array_diff( $required_methods, get_class_methods( 'Imagick' ) ) )
+		if ( array_udiff( $required_methods, get_class_methods( 'Imagick' ), 'strcasecmp') ) {
 			return false;
+		}
 
 		return true;
 	}