diff --git a/src/ethosu_device.c b/src/ethosu_device.c
index 2534bf6..935ec9e 100644
--- a/src/ethosu_device.c
+++ b/src/ethosu_device.c
@@ -403,6 +403,7 @@
 #if !defined(ARM_NPU_STUB)
     write_reg(NPU_REG_CMD, (uint32_t)irq_history_clear_mask << 16);
 #else
+    UNUSED(irq_history_clear_mask);
 #endif
     return ETHOSU_SUCCESS;
 }