diff --git a/include/sane/sanei_thread.h b/include/sane/sanei_thread.h
index e1f94e240..54e529318 100644
--- a/include/sane/sanei_thread.h
+++ b/include/sane/sanei_thread.h
@@ -141,7 +141,7 @@ extern SANE_Bool sanei_thread_is_valid (SANE_Pid pid);
  *  For details on the pthread_t type, see in particular Issue 6 of
  *  http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_types.h.html
  */
-#define sanei_thread_invalidate(sane_pid) ((sane_pid).pid = SANE_FALSE)
+#define sanei_thread_invalidate(sane_pid) ((sane_pid).is_valid = SANE_FALSE)
 
 /** Initialize a SANE_Pid
  *
diff --git a/sanei/sanei_thread.c b/sanei/sanei_thread.c
index d3005eacd..f0ed886ea 100644
--- a/sanei/sanei_thread.c
+++ b/sanei/sanei_thread.c
@@ -117,7 +117,7 @@ sanei_thread_is_forked( void )
 static void
 sanei_thread_set_invalid( SANE_Pid *pid )
 {
-  pid->is_valid = SANE_FALSE;
+	sanei_thread_invalidate(*pid);
 }
 #endif