diff --git a/H/dglobals.h b/H/dglobals.h
index 31d9cd8a6..6217998cd 100644
--- a/H/dglobals.h
+++ b/H/dglobals.h
@@ -71,7 +71,7 @@
 #endif /* THREADS */
 
 #define GLOBAL_Stream Yap_global->Stream_
-#if defined(THREADS)
+#if defined(THREADS)||defined(YAPOR)
 #define GLOBAL_StreamDescLock Yap_global->StreamDescLock_
 #endif
 
diff --git a/H/hglobals.h b/H/hglobals.h
index ca27f5f38..e8a37dfb7 100644
--- a/H/hglobals.h
+++ b/H/hglobals.h
@@ -71,7 +71,7 @@ typedef struct global_data {
 #endif /* THREADS */
 
   struct stream_desc*  Stream_;
-#if defined(THREADS)
+#if defined(THREADS)||defined(YAPOR)
   lockvar  StreamDescLock_;
 #endif
 
diff --git a/H/iglobals.h b/H/iglobals.h
index 9c4c900f4..ec47a0645 100644
--- a/H/iglobals.h
+++ b/H/iglobals.h
@@ -71,7 +71,7 @@ static void InitGlobal(void) {
 #endif /* THREADS */
 
 
-#if defined(THREADS)
+#if defined(THREADS)||defined(YAPOR)
   INIT_LOCK(GLOBAL_StreamDescLock);
 #endif
 
diff --git a/H/rglobals.h b/H/rglobals.h
index b2f04ff7b..13a01fb6f 100644
--- a/H/rglobals.h
+++ b/H/rglobals.h
@@ -71,7 +71,7 @@ static void RestoreGlobal(void) {
 #endif /* THREADS */
 
 
-#if defined(THREADS)
+#if defined(THREADS)||defined(YAPOR)
   REINIT_LOCK(GLOBAL_StreamDescLock);
 #endif