diff --git a/tools/libs/call/core.c b/tools/libs/call/core.c
index bbf88de9df..5ca037237f 100644
--- a/tools/libs/call/core.c
+++ b/tools/libs/call/core.c
@@ -24,6 +24,8 @@ xencall_handle *xencall_open(xentoollog_logger *logger, unsigned open_flags)
 
     if (!xcall) return NULL;
 
+    xcall->fd = -1;
+
     xcall->flags = open_flags;
     xcall->buffer_cache_nr = 0;
 
diff --git a/tools/libs/foreignmemory/core.c b/tools/libs/foreignmemory/core.c
index a5110a765c..a872b9555d 100644
--- a/tools/libs/foreignmemory/core.c
+++ b/tools/libs/foreignmemory/core.c
@@ -27,6 +27,7 @@ xenforeignmemory_handle *xenforeignmemory_open(xentoollog_logger *logger,
 
     if (!fmem) return NULL;
 
+    fmem->fd = -1;
     fmem->logger = logger;
     fmem->logger_tofree = NULL;