diff --git a/src/Input/FGLinuxEventInput.cxx b/src/Input/FGLinuxEventInput.cxx
index db40d9a78..60be218bb 100644
--- a/src/Input/FGLinuxEventInput.cxx
+++ b/src/Input/FGLinuxEventInput.cxx
@@ -26,6 +26,7 @@
 #include <cstdio>
 #include <sys/types.h>
 #include <sys/stat.h>
+#include <unistd.h>
 #include "FGLinuxEventInput.hxx"
 
 extern "C" {
diff --git a/utils/fgpanel/FGPanelApplication.cxx b/utils/fgpanel/FGPanelApplication.cxx
index d8ff4727e..1f5bbd654 100644
--- a/utils/fgpanel/FGPanelApplication.cxx
+++ b/utils/fgpanel/FGPanelApplication.cxx
@@ -21,8 +21,10 @@
 #endif
 
 #ifdef HAVE_WINDOWS_H
-#include <windows.h>
-#include <direct.h>
+#  include <windows.h>
+#  include <direct.h>
+#else
+#  include <unistd.h>
 #endif
 
 #ifdef __APPLE__