diff --git a/opcodes/riscv-dis.c b/opcodes/riscv-dis.c
index 101380f93aa..c1212b14a05 100644
--- a/opcodes/riscv-dis.c
+++ b/opcodes/riscv-dis.c
@@ -740,7 +740,7 @@ print_insn_args (const char *oparg, insn_t l, bfd_vma pc, disassemble_info *info
 		case 'i':
 		case 'I':
 		  print (info->stream, dis_style_address_offset,
-			 "%lu", EXTRACT_ZCMT_INDEX (l));
+			 "%" PRIu64, EXTRACT_ZCMT_INDEX (l));
 		  break;
 		default:
 		  goto undefined_modifier;