diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 45394cfe3289509fa9f80b8f967b638590111993..442f822f4242f4ac94834f5de4d9d4a7c6650a95 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -428,6 +428,10 @@ static int get_pci_config_device(QEMUFile *f, void *pv, size_t size)
     for (i = 0; i < size; ++i) {
         if ((config[i] ^ s->config[i]) &
             s->cmask[i] & ~s->wmask[i] & ~s->w1cmask[i]) {
+            error_report("%s: Bad config data: i=0x%x read: %x device: %x "
+                         "cmask: %x wmask: %x w1cmask:%x", __func__,
+                         i, config[i], s->config[i],
+                         s->cmask[i], s->wmask[i], s->w1cmask[i]);
             g_free(config);
             return -EINVAL;
         }