diff --git a/tools/firmware/hvmloader/smbios.c b/tools/firmware/hvmloader/smbios.c
index d8667f41ab..64fa799c0b 100644
--- a/tools/firmware/hvmloader/smbios.c
+++ b/tools/firmware/hvmloader/smbios.c
@@ -118,8 +118,9 @@ write_smbios_tables(void *start,
     do_struct(smbios_type_16_init(p, memsize, nr_mem_devs));
     for ( i = 0; i < nr_mem_devs; i++ )
     {
-        uint32_t dev_memsize = ((i == (nr_mem_devs - 1))
-                                ? (memsize & 0x3fff) : 0x4000);
+        uint32_t dev_memsize = 0x4000; /* all but last covers 16GB */
+        if ( (i == (nr_mem_devs - 1)) && ((memsize & 0x3fff) != 0) )
+            dev_memsize = memsize & 0x3fff; /* last dev is <16GB */
         do_struct(smbios_type_17_init(p, dev_memsize, i));
         do_struct(smbios_type_19_init(p, dev_memsize, i));
         do_struct(smbios_type_20_init(p, dev_memsize, i));