diff --git a/src/proto/os_win32.pro b/src/proto/os_win32.pro
index 188a45b..a87d8b7 100644
--- a/src/proto/os_win32.pro
+++ b/src/proto/os_win32.pro
@@ -67,5 +67,5 @@
 void set_alist_count(void);
 void fix_arg_enc(void);
 int mch_setenv(char *var, char *value, int x);
-void win32_build_env(dict_T *l, garray_T *gap);
+void win32_build_env(dict_T *l, garray_T *gap, int is_terminal);
 /* vim: set ft=c : */