diff --git a/src/util/virbuffer.c b/src/util/virbuffer.c
index 1a6bf122e0..3d6defb73a 100644
--- a/src/util/virbuffer.c
+++ b/src/util/virbuffer.c
@@ -883,6 +883,9 @@ virBufferStrcat(virBufferPtr buf, ...)
 {
     va_list ap;
 
+    if (!buf)
+        return;
+
     va_start(ap, buf);
     virBufferStrcatVArgs(buf, ap);
     va_end(ap);