diff --git a/mozilla/xpinstall/stub/xpistub.cpp b/mozilla/xpinstall/stub/xpistub.cpp
index 8a69ac55e31..536530a4717 100644
--- a/mozilla/xpinstall/stub/xpistub.cpp
+++ b/mozilla/xpinstall/stub/xpistub.cpp
@@ -58,6 +58,7 @@
 #endif
 
 #ifdef XP_UNIX
+#include <unistd.h>
 #define COMPONENT_REG "component.reg"
 #endif