diff --git a/arch/riscv/cpu/fu540/dram.c b/arch/riscv/cpu/fu540/dram.c
index 1fdc783..44e11bd 100644
--- a/arch/riscv/cpu/fu540/dram.c
+++ b/arch/riscv/cpu/fu540/dram.c
@@ -21,7 +21,7 @@
 	return fdtdec_setup_memory_banksize();
 }
 
-ulong board_get_usable_ram_top(ulong total_size)
+phys_size_t board_get_usable_ram_top(phys_size_t total_size)
 {
 	/*
 	 * Ensure that we run from first 4GB so that all