diff --git a/src/system.c b/src/system.c
index 4a5aac97..2b4094eb 100644
--- a/src/system.c
+++ b/src/system.c
@@ -17,7 +17,7 @@
 #define W 0
 
 #if RV32_HAS(SYSTEM) && !RV32_HAS(ELF_LOADER)
-void emu_update_uart_interrupts(riscv_t *rv)
+static void emu_update_uart_interrupts(riscv_t *rv)
 {
     vm_attr_t *attr = PRIV(rv);
     u8250_update_interrupts(attr->uart);