diff --git a/simgear/package/untar.cxx b/simgear/package/untar.cxx
index 9eb0901c..1ae4f08d 100644
--- a/simgear/package/untar.cxx
+++ b/simgear/package/untar.cxx
@@ -20,6 +20,8 @@
 #include <cstdlib>
 #include <cassert>
 #include <cstdint>
+#include <cstring>
+#include <cstddef>
 
 #include <zlib.h>