diff --git a/arch/arm/include/debug/zynq.S b/arch/arm/include/debug/zynq.S
index bd13dedbdeff..de86b9247564 100644
--- a/arch/arm/include/debug/zynq.S
+++ b/arch/arm/include/debug/zynq.S
@@ -38,7 +38,7 @@
 		.endm
 
 		.macro	senduart,rd,rx
-		str	\rd, [\rx, #UART_FIFO_OFFSET]	@ TXDATA
+		strb	\rd, [\rx, #UART_FIFO_OFFSET]	@ TXDATA
 		.endm
 
 		.macro	waituart,rd,rx