diff --git a/src/lua/endpoints/api_get.lua b/src/lua/endpoints/api_get.lua
index 99dd228..b9f9796 100644
--- a/src/lua/endpoints/api_get.lua
+++ b/src/lua/endpoints/api_get.lua
@@ -36,7 +36,7 @@ local function api_get(req)
 		we're searching for, potentially causing a DoS with a
 		sufficiently backtrack-ey search/tag combination.
 		]]
-		assert(data:match("^[a-zA-Z0-9,%s-]+$"),"Bad characters in tag")
+		assert(data:match("^[a-zA-Z0-9,%s-]+$"),string.format("Bad characters in tag: %q",data))
 		return suggest_tags(req,data)
 	end
 end