diff --git a/include/os.h b/include/os.h
index facfa7047..2d164563a 100644
--- a/include/os.h
+++ b/include/os.h
@@ -86,8 +86,6 @@ typedef struct _NewClientRec *NewClientPtr;
 
 extern _X_EXPORT int ReadFdFromClient(ClientPtr client);
 
-extern _X_EXPORT void FlushAllOutput(void);
-
 extern _X_EXPORT void FlushIfCriticalOutputPending(void);
 
 extern _X_EXPORT void SetCriticalOutputPending(void);
diff --git a/os/WaitFor.c b/os/WaitFor.c
index 7f64c336b..a616850ab 100644
--- a/os/WaitFor.c
+++ b/os/WaitFor.c
@@ -64,6 +64,7 @@ SOFTWARE.
 
 #include "dix/dix_priv.h"
 #include "os/busfault.h"
+#include "os/client_priv.h"
 #include "os/screensaver.h"
 
 #include "misc.h"
diff --git a/os/client_priv.h b/os/client_priv.h
index 90f0e1afe..04649c8d4 100644
--- a/os/client_priv.h
+++ b/os/client_priv.h
@@ -46,6 +46,7 @@ void ListenOnOpenFD(int fd, int noxauth);
 int ReadRequestFromClient(struct _Client *client);
 int WriteFdToClient(struct _Client *client, int fd, Bool do_close);
 Bool InsertFakeRequest(struct _Client *client, char *data, int count);
+void FlushAllOutput(void);
 
 /* exported only for DRI module, but should not be used by external drivers */
 _X_EXPORT void ResetCurrentRequest(struct _Client *client);