diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index e8dfc7013d..5d8f7479bb 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1295,6 +1295,7 @@ FWCfgState *pc_memory_init(PCMachineState *pcms,
     MemoryRegion *ram_below_4g, *ram_above_4g;
     FWCfgState *fw_cfg;
     MachineState *machine = MACHINE(pcms);
+    PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
 
     assert(machine->ram_size == pcms->below_4g_mem_size +
                                 pcms->above_4g_mem_size);
@@ -1356,7 +1357,7 @@ FWCfgState *pc_memory_init(PCMachineState *pcms,
         pcms->hotplug_memory.base =
             ROUND_UP(0x100000000ULL + pcms->above_4g_mem_size, 1ULL << 30);
 
-        if (pcms->enforce_aligned_dimm) {
+        if (pcmc->enforce_aligned_dimm) {
             /* size hotplug region assuming 1G page max alignment per slot */
             hotplug_mem_size += (1ULL << 30) * machine->ram_slots;
         }
@@ -1609,12 +1610,13 @@ static void pc_dimm_plug(HotplugHandler *hotplug_dev,
     HotplugHandlerClass *hhc;
     Error *local_err = NULL;
     PCMachineState *pcms = PC_MACHINE(hotplug_dev);
+    PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(pcms);
     PCDIMMDevice *dimm = PC_DIMM(dev);
     PCDIMMDeviceClass *ddc = PC_DIMM_GET_CLASS(dimm);
     MemoryRegion *mr = ddc->get_memory_region(dimm);
     uint64_t align = TARGET_PAGE_SIZE;
 
-    if (memory_region_get_alignment(mr) && pcms->enforce_aligned_dimm) {
+    if (memory_region_get_alignment(mr) && pcmc->enforce_aligned_dimm) {
         align = memory_region_get_alignment(mr);
     }
 
@@ -1865,9 +1867,9 @@ static void pc_machine_set_smm(Object *obj, Visitor *v, void *opaque,
 
 static bool pc_machine_get_aligned_dimm(Object *obj, Error **errp)
 {
-    PCMachineState *pcms = PC_MACHINE(obj);
+    PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(obj);
 
-    return pcms->enforce_aligned_dimm;
+    return pcmc->enforce_aligned_dimm;
 }
 
 static void pc_machine_initfn(Object *obj)
@@ -1905,7 +1907,6 @@ static void pc_machine_initfn(Object *obj)
                                     "Enable vmport (pc & q35)",
                                     &error_abort);
 
-    pcms->enforce_aligned_dimm = true;
     object_property_add_bool(obj, PC_MACHINE_ENFORCE_ALIGNED_DIMM,
                              pc_machine_get_aligned_dimm,
                              NULL, &error_abort);
@@ -1953,6 +1954,7 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
     pcmc->gigabyte_align = true;
     pcmc->has_reserved_memory = true;
     pcmc->kvmclock_enabled = true;
+    pcmc->enforce_aligned_dimm = true;
     /* BIOS ACPI tables: 128K. Other BIOS datastructures: less than 4K reported
      * to be used at the moment, 32K should be enough for a while.  */
     pcmc->acpi_data_size = 0x20000 + 0x8000;
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 82b8a5e74f..f058b3cb00 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -308,11 +308,8 @@ static void pc_compat_2_2(MachineState *machine)
 
 static void pc_compat_2_1(MachineState *machine)
 {
-    PCMachineState *pcms = PC_MACHINE(machine);
-
     pc_compat_2_2(machine);
     x86_cpu_change_kvm_default("svm", NULL);
-    pcms->enforce_aligned_dimm = false;
 }
 
 static void pc_compat_2_0(MachineState *machine)
@@ -484,6 +481,7 @@ static void pc_i440fx_2_1_machine_options(MachineClass *m)
     m->default_display = NULL;
     SET_MACHINE_COMPAT(m, PC_COMPAT_2_1);
     pcmc->smbios_uuid_encoded = false;
+    pcmc->enforce_aligned_dimm = false;
 }
 
 DEFINE_I440FX_MACHINE(v2_1, "pc-i440fx-2.1", pc_compat_2_1,
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index cc85d3a475..2f644f951d 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -292,10 +292,7 @@ static void pc_compat_2_2(MachineState *machine)
 
 static void pc_compat_2_1(MachineState *machine)
 {
-    PCMachineState *pcms = PC_MACHINE(machine);
-
     pc_compat_2_2(machine);
-    pcms->enforce_aligned_dimm = false;
     x86_cpu_change_kvm_default("svm", NULL);
 }
 
@@ -409,6 +406,7 @@ static void pc_q35_2_1_machine_options(MachineClass *m)
     m->default_display = NULL;
     SET_MACHINE_COMPAT(m, PC_COMPAT_2_1);
     pcmc->smbios_uuid_encoded = false;
+    pcmc->enforce_aligned_dimm = false;
 }
 
 DEFINE_Q35_MACHINE(v2_1, "pc-q35-2.1", pc_compat_2_1,
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 3edae2bfa8..d1dc63ceb8 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -36,8 +36,6 @@
 /**
  * PCMachineState:
  * @acpi_dev: link to ACPI PM device that performs ACPI hotplug handling
- * @enforce_aligned_dimm: check that DIMM's address/size is aligned by
- *                        backend's alignment value if provided
  */
 struct PCMachineState {
     /*< private >*/
@@ -52,7 +50,6 @@ struct PCMachineState {
     uint64_t max_ram_below_4g;
     OnOffAuto vmport;
     OnOffAuto smm;
-    bool enforce_aligned_dimm;
     ram_addr_t below_4g_mem_size, above_4g_mem_size;
 };
 
@@ -66,6 +63,8 @@ struct PCMachineState {
 /**
  * PCMachineClass:
  * @get_hotplug_handler: pointer to parent class callback @get_hotplug_handler
+ * @enforce_aligned_dimm: check that DIMM's address/size is aligned by
+ *                        backend's alignment value if provided
  */
 struct PCMachineClass {
     /*< private >*/
@@ -94,6 +93,7 @@ struct PCMachineClass {
      * and other BIOS datastructures.
      */
     unsigned acpi_data_size;
+    bool enforce_aligned_dimm;
 };
 
 #define TYPE_PC_MACHINE "generic-pc-machine"