diff --git a/image.php b/image.php
index ca95417d..4151a7b0 100644
--- a/image.php
+++ b/image.php
@@ -76,13 +76,13 @@ get_header();
 								}
 							?>
 
-							<a href="<?php echo $next_attachment_url; ?>" title="<?php the_title_attribute(); ?>" rel="attachment"><?php
+							<a href="<?php echo esc_url( $next_attachment_url ); ?>" title="<?php the_title_attribute(); ?>" rel="attachment"><?php
 								$attachment_size = apply_filters( '_s_attachment_size', array( 1200, 1200 ) ); // Filterable image size.
-								echo wp_get_attachment_image( $post->ID, $attachment_size );
+								echo wp_get_attachment_image( get_the_ID(), $attachment_size );
 							?></a>
 						</div><!-- .attachment -->
 
-						<?php if ( ! empty( $post->post_excerpt ) ) : ?>
+						<?php if ( has_excerpt() ) : ?>
 						<div class="entry-caption">
 							<?php the_excerpt(); ?>
 						</div><!-- .entry-caption -->