diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
index 6ad05ca..ea90b64 100644
--- a/include/exec/exec-all.h
+++ b/include/exec/exec-all.h
@@ -322,7 +322,7 @@
 
 #if !defined(CONFIG_USER_ONLY)
 
-void phys_mem_set_alloc(void *(*alloc)(ram_addr_t));
+void phys_mem_set_alloc(void *(*alloc)(size_t));
 
 struct MemoryRegion *iotlb_to_region(hwaddr index);
 bool io_mem_read(struct MemoryRegion *mr, hwaddr addr,