diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index 417ff647fb37..06fb50218136 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -49,6 +49,7 @@ void __init mem_init(void)
 	map_memory(brk_end, __pa(brk_end), uml_reserved - brk_end, 1, 1, 0);
 	memblock_free(__pa(brk_end), uml_reserved - brk_end);
 	uml_reserved = brk_end;
+	min_low_pfn = PFN_UP(__pa(uml_reserved));
 
 	/* this will put all low memory onto the freelists */
 	memblock_free_all();