diff --git a/wp-includes/post-template.php b/wp-includes/post-template.php
index 31b349d414..443f0c6d1d 100644
--- a/wp-includes/post-template.php
+++ b/wp-includes/post-template.php
@@ -349,8 +349,6 @@ function get_attachment_icon_src( $id = 0, $fullsize = false ) {
 
 	$file = get_attached_file( $post->ID );
 
-	$exts = array('jpg', 'gif', 'png');
-
 	if ( !$fullsize && $thumbfile = wp_get_attachment_thumb_file( $post->ID ) ) {
 		// We have a thumbnail desired, specified and existing
 
diff --git a/wp-includes/post.php b/wp-includes/post.php
index 25c1fb367a..c55fb657af 100644
--- a/wp-includes/post.php
+++ b/wp-includes/post.php
@@ -1471,9 +1471,11 @@ function wp_attachment_is_image( $post_id = 0 ) {
 	if ( !$file = get_attached_file( $post->ID ) )
 		return false;
 
-	$image_exts = array('/jpg', 'jpeg', '/gif', '/png');
+	$ext = preg_match('/\.([^.]+)$/', $file, $matches) ? strtolower($matches[1]) : false;
 
-	if ( 'image/' == substr($post->post_mime_type, 0, 6) || 'import' == $post->post_mime_type && in_array(substr($file, -4), $exts) )
+	$image_exts = array('jpg', 'jpeg', 'gif', 'png');
+
+	if ( 'image/' == substr($post->post_mime_type, 0, 6) || $ext && 'import' == $post->post_mime_type && in_array($ext, $image_exts) )
 		return true;
 	return false;
 }