diff --git a/backends/hostmem.c b/backends/hostmem.c
index 4e5576a4ad..181446626a 100644
--- a/backends/hostmem.c
+++ b/backends/hostmem.c
@@ -178,7 +178,7 @@ static void host_memory_backend_set_merge(Object *obj, bool value, Error **errp)
         return;
     }
 
-    if (!host_memory_backend_mr_inited(backend) &&
+    if (host_memory_backend_mr_inited(backend) &&
         value != backend->merge) {
         void *ptr = memory_region_get_ram_ptr(&backend->mr);
         uint64_t sz = memory_region_size(&backend->mr);