diff --git a/hw/i2c/aspeed_i2c.c b/hw/i2c/aspeed_i2c.c
index faf2160c06..1b8ac561c3 100644
--- a/hw/i2c/aspeed_i2c.c
+++ b/hw/i2c/aspeed_i2c.c
@@ -656,8 +656,6 @@ static void aspeed_i2c_bus_new_write(AspeedI2CBus *bus, hwaddr offset,
         bus->dma_dram_offset =
             deposit64(bus->dma_dram_offset, 0, 32,
                       FIELD_EX32(value, I2CM_DMA_TX_ADDR, ADDR));
-        bus->regs[R_I2CC_DMA_LEN] = ARRAY_FIELD_EX32(bus->regs, I2CM_DMA_LEN,
-                                                     TX_BUF_LEN) + 1;
         break;
     case A_I2CM_DMA_RX_ADDR:
         bus->regs[R_I2CM_DMA_RX_ADDR] = FIELD_EX32(value, I2CM_DMA_RX_ADDR,
@@ -665,8 +663,6 @@ static void aspeed_i2c_bus_new_write(AspeedI2CBus *bus, hwaddr offset,
         bus->dma_dram_offset =
             deposit64(bus->dma_dram_offset, 0, 32,
                       FIELD_EX32(value, I2CM_DMA_RX_ADDR, ADDR));
-        bus->regs[R_I2CC_DMA_LEN] = ARRAY_FIELD_EX32(bus->regs, I2CM_DMA_LEN,
-                                                     RX_BUF_LEN) + 1;
         break;
     case A_I2CM_DMA_LEN:
         w1t = FIELD_EX32(value, I2CM_DMA_LEN, RX_BUF_LEN_W1T) ||
@@ -679,10 +675,16 @@ static void aspeed_i2c_bus_new_write(AspeedI2CBus *bus, hwaddr offset,
         if (FIELD_EX32(value, I2CM_DMA_LEN, RX_BUF_LEN_W1T)) {
             ARRAY_FIELD_DP32(bus->regs, I2CM_DMA_LEN, RX_BUF_LEN,
                              FIELD_EX32(value, I2CM_DMA_LEN, RX_BUF_LEN));
+            bus->regs[R_I2CC_DMA_LEN] = ARRAY_FIELD_EX32(bus->regs,
+                                                         I2CM_DMA_LEN,
+                                                         RX_BUF_LEN) + 1;
         }
         if (FIELD_EX32(value, I2CM_DMA_LEN, TX_BUF_LEN_W1T)) {
             ARRAY_FIELD_DP32(bus->regs, I2CM_DMA_LEN, TX_BUF_LEN,
                              FIELD_EX32(value, I2CM_DMA_LEN, TX_BUF_LEN));
+            bus->regs[R_I2CC_DMA_LEN] = ARRAY_FIELD_EX32(bus->regs,
+                                                         I2CM_DMA_LEN,
+                                                         TX_BUF_LEN) + 1;
         }
         break;
     case A_I2CM_DMA_LEN_STS: