diff --git a/panda/src/express/multifile.cxx b/panda/src/express/multifile.cxx
index dd858d8f33..a5c2ab5de9 100644
--- a/panda/src/express/multifile.cxx
+++ b/panda/src/express/multifile.cxx
@@ -19,9 +19,11 @@
 #include <pandabase.h>
 #include "multifile.h"
 #include "config_express.h"
-#include <algorithm>
 #include "error_utils.h"
 
+#include <algorithm>
+#include <errno.h>
+
 ////////////////////////////////////////////////////////////////////
 // Defines
 ////////////////////////////////////////////////////////////////////