diff --git a/code/controllers/subsystem/blackbox.dm b/code/controllers/subsystem/blackbox.dm
index 3a0f3cff24..96c195f1b7 100644
--- a/code/controllers/subsystem/blackbox.dm
+++ b/code/controllers/subsystem/blackbox.dm
@@ -218,6 +218,8 @@ Versioning
 			FV.json["data"]["[pos]"] = list() //in 512 "pos" can be replaced with "[FV.json["data"].len+1]"
 			for(var/i in data)
 				FV.json["data"]["[pos]"]["[i]"] = "[data[i]]" //and here with "[FV.json["data"].len]"
+		else
+			CRASH("Invalid feedback key_type: [key_type]")
 
 /datum/controller/subsystem/blackbox/proc/record_feedback_recurse_list(list/L, list/key_list, increment, depth = 1)
 	if(depth == key_list.len)