diff --git a/board/czechlight/clearfog/linux.fragment b/board/czechlight/clearfog/linux.fragment
index 5d353f4..08a0352 100644
--- a/board/czechlight/clearfog/linux.fragment
+++ b/board/czechlight/clearfog/linux.fragment
@@ -29,6 +29,10 @@
 CONFIG_SFP=y
 CONFIG_IGB=y
 
+# optoswitch PCB
+CONFIG_IIO=y
+CONFIG_AD5593R=y
+
 CONFIG_MACH_ARMADA_370=n
 CONFIG_MACH_ARMADA_375=n
 CONFIG_MACH_ARMADA_39X=n