diff --git a/hw/misc/aspeed_scu.c b/hw/misc/aspeed_scu.c
index 76cfd91671..6703f3f969 100644
--- a/hw/misc/aspeed_scu.c
+++ b/hw/misc/aspeed_scu.c
@@ -427,6 +427,10 @@ static const MemoryRegionOps aspeed_ast2400_scu_ops = {
     .read = aspeed_scu_read,
     .write = aspeed_ast2400_scu_write,
     .endianness = DEVICE_LITTLE_ENDIAN,
+    .impl = {
+        .min_access_size = 4,
+        .max_access_size = 4,
+    },
     .valid = {
         .min_access_size = 1,
         .max_access_size = 4,
@@ -437,6 +441,8 @@ static const MemoryRegionOps aspeed_ast2500_scu_ops = {
     .read = aspeed_scu_read,
     .write = aspeed_ast2500_scu_write,
     .endianness = DEVICE_LITTLE_ENDIAN,
+    .impl.min_access_size = 4,
+    .impl.max_access_size = 4,
     .valid.min_access_size = 4,
     .valid.max_access_size = 4,
     .valid.unaligned = false,
@@ -779,6 +785,8 @@ static const MemoryRegionOps aspeed_ast2600_scu_ops = {
     .read = aspeed_ast2600_scu_read,
     .write = aspeed_ast2600_scu_write,
     .endianness = DEVICE_LITTLE_ENDIAN,
+    .impl.min_access_size = 4,
+    .impl.max_access_size = 4,
     .valid.min_access_size = 4,
     .valid.max_access_size = 4,
     .valid.unaligned = false,
@@ -906,6 +914,8 @@ static const MemoryRegionOps aspeed_ast2700_scu_ops = {
     .read = aspeed_ast2700_scu_read,
     .write = aspeed_ast2700_scu_write,
     .endianness = DEVICE_LITTLE_ENDIAN,
+    .impl.min_access_size = 4,
+    .impl.max_access_size = 4,
     .valid.min_access_size = 1,
     .valid.max_access_size = 8,
     .valid.unaligned = false,
@@ -1028,6 +1038,8 @@ static const MemoryRegionOps aspeed_ast2700_scuio_ops = {
     .read = aspeed_ast2700_scuio_read,
     .write = aspeed_ast2700_scuio_write,
     .endianness = DEVICE_LITTLE_ENDIAN,
+    .impl.min_access_size = 4,
+    .impl.max_access_size = 4,
     .valid.min_access_size = 1,
     .valid.max_access_size = 8,
     .valid.unaligned = false,