diff --git a/mozilla/layout/html/forms/src/nsForm.cpp b/mozilla/layout/html/forms/src/nsForm.cpp
index 758682cf776..2a01f0a07a5 100644
--- a/mozilla/layout/html/forms/src/nsForm.cpp
+++ b/mozilla/layout/html/forms/src/nsForm.cpp
@@ -45,6 +45,7 @@
 #include "xp_file.h"
 #include "prio.h"
 #include "prmem.h"
+#include "prenv.h"
 
 #define CRLF "\015\012"