diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
index 59c7a81692..82d37cb376 100644
--- a/hw/i386/pc_sysfw.c
+++ b/hw/i386/pc_sysfw.c
@@ -40,11 +40,10 @@
 
 #define FLASH_SECTOR_SIZE 4096
 
-static void pc_isa_bios_init(MemoryRegion *rom_memory,
+static void pc_isa_bios_init(MemoryRegion *isa_bios, MemoryRegion *rom_memory,
                              MemoryRegion *flash_mem)
 {
     int isa_bios_size;
-    MemoryRegion *isa_bios;
     uint64_t flash_size;
     void *flash_ptr, *isa_bios_ptr;
 
@@ -52,7 +51,6 @@ static void pc_isa_bios_init(MemoryRegion *rom_memory,
 
     /* map the last 128KB of the BIOS in ISA space */
     isa_bios_size = MIN(flash_size, 128 * KiB);
-    isa_bios = g_malloc(sizeof(*isa_bios));
     memory_region_init_ram(isa_bios, NULL, "isa-bios", isa_bios_size,
                            &error_fatal);
     memory_region_add_subregion_overlap(rom_memory,
@@ -136,6 +134,7 @@ void pc_system_flash_cleanup_unused(PCMachineState *pcms)
 static void pc_system_flash_map(PCMachineState *pcms,
                                 MemoryRegion *rom_memory)
 {
+    X86MachineState *x86ms = X86_MACHINE(pcms);
     hwaddr total_size = 0;
     int i;
     BlockBackend *blk;
@@ -185,7 +184,7 @@ static void pc_system_flash_map(PCMachineState *pcms,
 
         if (i == 0) {
             flash_mem = pflash_cfi01_get_memory(system_flash);
-            pc_isa_bios_init(rom_memory, flash_mem);
+            pc_isa_bios_init(&x86ms->isa_bios, rom_memory, flash_mem);
 
             /* Encrypt the pflash boot ROM */
             if (sev_enabled()) {
diff --git a/hw/i386/x86.c b/hw/i386/x86.c
index 6d3c72f124..457e8a34a5 100644
--- a/hw/i386/x86.c
+++ b/hw/i386/x86.c
@@ -1133,7 +1133,7 @@ void x86_bios_rom_init(X86MachineState *x86ms, const char *default_firmware,
 {
     const char *bios_name;
     char *filename;
-    MemoryRegion *bios, *isa_bios;
+    MemoryRegion *bios;
     int bios_size, isa_bios_size;
     ssize_t ret;
 
@@ -1173,14 +1173,13 @@ void x86_bios_rom_init(X86MachineState *x86ms, const char *default_firmware,
 
     /* map the last 128KB of the BIOS in ISA space */
     isa_bios_size = MIN(bios_size, 128 * KiB);
-    isa_bios = g_malloc(sizeof(*isa_bios));
-    memory_region_init_alias(isa_bios, NULL, "isa-bios", bios,
+    memory_region_init_alias(&x86ms->isa_bios, NULL, "isa-bios", bios,
                              bios_size - isa_bios_size, isa_bios_size);
     memory_region_add_subregion_overlap(rom_memory,
                                         0x100000 - isa_bios_size,
-                                        isa_bios,
+                                        &x86ms->isa_bios,
                                         1);
-    memory_region_set_readonly(isa_bios, !isapc_ram_fw);
+    memory_region_set_readonly(&x86ms->isa_bios, !isapc_ram_fw);
 
     /* map all the bios at the top of memory */
     memory_region_add_subregion(rom_memory,
diff --git a/include/hw/i386/x86.h b/include/hw/i386/x86.h
index cb07618d19..a07de79167 100644
--- a/include/hw/i386/x86.h
+++ b/include/hw/i386/x86.h
@@ -18,6 +18,7 @@
 #define HW_I386_X86_H
 
 #include "exec/hwaddr.h"
+#include "exec/memory.h"
 
 #include "hw/boards.h"
 #include "hw/intc/ioapic.h"
@@ -52,6 +53,12 @@ struct X86MachineState {
     GMappedFile *initrd_mapped_file;
     HotplugHandler *acpi_dev;
 
+    /*
+     * Map the upper 128 KiB of the BIOS just underneath the 1 MiB address
+     * boundary.
+     */
+    MemoryRegion isa_bios;
+
     /* RAM information (sizes, addresses, configuration): */
     ram_addr_t below_4g_mem_size, above_4g_mem_size;