Thumbview.cc:487:26: warning: format specifies type 'long' but the argument
has type 'time_t' (aka 'long long') [-Wformat]

Index: src/Thumbview.cc
--- src/Thumbview.cc.orig
+++ src/Thumbview.cc
@@ -484,7 +484,7 @@ void Thumbview::create_cache_images()
 		time_t mtime = get_file_mtime(file);
 
 		char *bufout = new char[20];
-		sprintf(bufout, "%ld", mtime);
+		sprintf(bufout, "%lld", mtime);
 
 		opts.push_back(Glib::ustring("tEXt::Thumb::MTime"));
 		vals.push_back(Glib::ustring(bufout));