diff --git a/drivers/serial/Kconfig-16550 b/drivers/serial/Kconfig-16550
index 259240dfb7..b54b72990f 100644
--- a/drivers/serial/Kconfig-16550
+++ b/drivers/serial/Kconfig-16550
@@ -347,6 +347,8 @@ config 16550_ADDRWIDTH
 	int "Address width of 16550 registers"
 	default 8
 	---help---
-		The bit width of registers.  Options are 8, 16, or 32. Default: 8
+		The bit width of registers.  Options are 0, 8, 16, or 32.
+		Default: 8
+		Note: 0 means auto detect address size (uintptr_t)
 
 endif # 16550_UART
diff --git a/include/nuttx/serial/uart_16550.h b/include/nuttx/serial/uart_16550.h
index 88295dc1d8..102db0407a 100644
--- a/include/nuttx/serial/uart_16550.h
+++ b/include/nuttx/serial/uart_16550.h
@@ -68,8 +68,9 @@
 #  error "CONFIG_16550_ADDRWIDTH not defined"
 #endif
 
-#if CONFIG_16550_ADDRWIDTH != 8 && CONFIG_16550_ADDRWIDTH != 16 && \
-    CONFIG_16550_ADDRWIDTH != 32 && CONFIG_16550_ADDRWIDTH != 64
+#if CONFIG_16550_ADDRWIDTH != 0 && CONFIG_16550_ADDRWIDTH != 8 && \
+    CONFIG_16550_ADDRWIDTH != 16 && CONFIG_16550_ADDRWIDTH != 32 && \
+    CONFIG_16550_ADDRWIDTH != 64
 #  error "CONFIG_16550_ADDRWIDTH not supported"
 #endif
 
@@ -309,7 +310,9 @@ typedef uint16_t uart_datawidth_t;
 typedef uint32_t uart_datawidth_t;
 #endif
 
-#if CONFIG_16550_ADDRWIDTH == 8
+#if CONFIG_16550_ADDRWIDTH == 0
+typedef uintptr_t uart_addrwidth_t;
+#elif CONFIG_16550_ADDRWIDTH == 8
 typedef uint8_t uart_addrwidth_t;
 #elif CONFIG_16550_ADDRWIDTH == 16
 typedef uint16_t uart_addrwidth_t;