diff --git a/tests/emurt/emurt.c b/tests/emurt/emurt.c
index 9ae15de55..24a2de395 100644
--- a/tests/emurt/emurt.c
+++ b/tests/emurt/emurt.c
@@ -4,7 +4,7 @@
 #define UART_W_REG 0x10000010
 #define PERF_REG 0x10000014
 
-void t1_put_char(char c) { *(uint8_t volatile *)(UART_W_REG) = (uint8_t)c; }
+void t1_put_char(char c) { *(uint32_t volatile *)(UART_W_REG) = (uint8_t)c; }
 void place_counter(int i) { *(int volatile *)(PERF_REG) = i; }
 
 ///////////////////////