diff --git a/hw/core/platform-bus.c b/hw/core/platform-bus.c
index b8487b26b6..dc58bf505a 100644
--- a/hw/core/platform-bus.c
+++ b/hw/core/platform-bus.c
@@ -145,9 +145,12 @@ static void platform_bus_map_mmio(PlatformBusDevice *pbus, SysBusDevice *sbdev,
      * the target device's memory region
      */
     for (off = 0; off < pbus->mmio_size; off += alignment) {
-        if (!memory_region_find(&pbus->mmio, off, size).mr) {
+        MemoryRegion *mr = memory_region_find(&pbus->mmio, off, size).mr;
+        if (!mr) {
             found_region = true;
             break;
+        } else {
+            memory_region_unref(mr);
         }
     }