diff --git a/src/serial.s b/src/serial.s
index 6c35585..5da47c9 100644
--- a/src/serial.s
+++ b/src/serial.s
@@ -85,14 +85,15 @@ END@
 
 ; Reads a char in polled mode non-FIFO mode (INITUART state).
 ; A: Filled with char from RX buffer or NUL ($00) if no char is ready
+; B: Filled with LSR status codes masked with $9F
 PINCHAR
-  lda UART_LSR ; See if a char is ready
+  ldb UART_LSR       ; See if a char is ready
   ; Mask of possible UART error codes | data ready flag ($9F)
-  anda #(UARTF_LSR_DR|UARTF_LSR_OE|UARTF_LSR_PE|UARTF_LSR_FE|UARTF_LSR_BI|UARTF_LSR_FIFO)
-  bita #UARTF_LSR_DR
+  andb #(UARTF_LSR_DR|UARTF_LSR_OE|UARTF_LSR_PE|UARTF_LSR_FE|UARTF_LSR_BI|UARTF_LSR_FIFO)
+  bitb #UARTF_LSR_DR ; Check for char
   beq NOCHAR@
-  lda UART_RBR ; Pull char from RX buffer
+  lda UART_RBR       ; Pull char from RX buffer
   rts
 NOCHAR@
-  clra         ; Fill A with '\0'.
+  clra               ; Fill A with '\0'.
   rts