diff --git a/lua/zones.lua b/lua/zones.lua
index f95d6f2..3a9396e 100644
--- a/lua/zones.lua
+++ b/lua/zones.lua
@@ -134,6 +134,9 @@ end
 
 --Gets a list of all zones which are of the specified class.
 function zones.FindByClass(class)
+	if (not isstring(class)) then return zones.List end
+	if class == "" then return zones.List end
+	
 	local tbl = {}
 
 	for k,v in pairs(zones.List) do
@@ -608,4 +611,4 @@ function zones.PointInPoly(point,poly) //True if point is within a polygon.
 	end
 
 	return inside
-end
\ No newline at end of file
+end