diff --git a/file_download.php b/file_download.php
index 67bc832a5e..705fc095a0 100644
--- a/file_download.php
+++ b/file_download.php
@@ -190,13 +190,24 @@
 	$t_content_type = $t_content_type_override;
 }
 
-# Don't allow inline flash
-if( false !== strpos( $t_content_type, 'application/x-shockwave-flash' ) ) {
-	http_content_disposition_header( $t_filename );
-} else {
-	http_content_disposition_header( $t_filename, $f_show_inline );
+# Decide what should open inline in the browser vs. download as attachment
+# https://www.thoughtco.com/mime-types-by-content-type-3469108
+$t_show_inline = $f_show_inline;
+$t_mime_force_inline = array(
+	'image/jpeg', 'image/gif', 'image/tiff', 'image/bmp', 'image/svg+xml', 'image/png',
+	);
+$t_mime_force_attachment = array( 'application/x-shockwave-flash' );
+
+$t_mime_type = substr( $t_content_type, 0, strpos( $t_content_type, ';' ) );
+
+if( in_array( $t_mime_type, $t_mime_force_inline ) ) {
+	$t_show_inline = true;
+} else if( in_array( $t_mime_type, $t_mime_force_attachment ) ) {
+	$t_show_inline = false;
 }
 
+http_content_disposition_header( $t_filename, $t_show_inline );
+
 header( 'Content-Type: ' . $t_content_type );
 header( 'Content-Length: ' . $v_filesize );