diff --git a/tools/python/xen/lowlevel/xs/xs.c b/tools/python/xen/lowlevel/xs/xs.c
index ea50f86bc3..621039d7a7 100644
--- a/tools/python/xen/lowlevel/xs/xs.c
+++ b/tools/python/xen/lowlevel/xs/xs.c
@@ -531,6 +531,7 @@ again:
     free(xsval);
 
     if (!val && errno == EAGAIN) {
+        PyErr_Clear();
         goto again;
     }