diff --git a/arch/arm/src/imxrt/imxrt_serial.c b/arch/arm/src/imxrt/imxrt_serial.c
index 30a487b5536..939ccc6e58a 100644
--- a/arch/arm/src/imxrt/imxrt_serial.c
+++ b/arch/arm/src/imxrt/imxrt_serial.c
@@ -1375,7 +1375,7 @@ static int imxrt_dma_nextrx(struct imxrt_uart_s *priv)
   int dmaresidual = imxrt_dmach_getcount(priv->rxdma);
   DEBUGASSERT(dmaresidual <= RXDMA_BUFFER_SIZE);
 
-  return RXDMA_BUFFER_SIZE - dmaresidual;
+  return (RXDMA_BUFFER_SIZE - dmaresidual) % RXDMA_BUFFER_SIZE;
 }
 #endif