diff --git a/lib/shared/ids.lua b/lib/shared/ids.lua
index 17a3099..3091b9b 100644
--- a/lib/shared/ids.lua
+++ b/lib/shared/ids.lua
@@ -8,7 +8,8 @@ Ids.CreateUniqueId = function(tbl, len, pattern) -- both optional
     for i = 1, len do
         local char = ""
         if pattern then
-            char = pattern:sub(math.random(1, #pattern), math.random(1, #pattern))
+            local charIndex = math.random(1, #pattern)
+            char = pattern:sub(charIndex, charIndex)
         else
             char = math.random(1, 2) == 1 and string.char(math.random(65, 90)) or math.random(0, 9) -- CAP letter and number
         end