diff --git a/cpu/esp32/periph/uart.c b/cpu/esp32/periph/uart.c
index 7e5be792cbbc..7ea886579cc3 100644
--- a/cpu/esp32/periph/uart.c
+++ b/cpu/esp32/periph/uart.c
@@ -240,7 +240,7 @@ void uart_print_config(void)
     }
 }
 
-void IRAM _uart_intr_handler (void *arg)
+static void IRAM _uart_intr_handler (void *arg)
 {
     /* to satisfy the compiler */
     (void)arg;