add default nettype none
diff --git a/verilog/rtl/housekeeping_spi.v b/verilog/rtl/housekeeping_spi.v
index cc8d5d0..bd09dcb 100644
--- a/verilog/rtl/housekeeping_spi.v
+++ b/verilog/rtl/housekeeping_spi.v
@@ -1,3 +1,4 @@
+`default_nettype none
 //-------------------------------------
 // SPI controller for Caravel (PicoSoC)
 //-------------------------------------