diff --git a/bs/TagEngine.bs b/bs/TagEngine.bs
index cb21845..aceebc2 100644
--- a/bs/TagEngine.bs
+++ b/bs/TagEngine.bs
@@ -5,21 +5,21 @@ import Util
 
 #define UIntLog2N(n) (UInt (TLog n))
 
-data Tag a
-    = Next (UInt a)
-    | Empty
+data Tag numTags
+    = Next UIntLog2N(numTags)
+    | Tail
     deriving (Bits, Eq, FShow)
 
-initTagNext :: Integer -> Module(Reg (Tag a))
+initTagNext :: Integer -> Module(Reg (Tag numTags))
 initTagNext i = do
-    t :: Reg (Tag a)
+    t :: Reg (Tag numTags)
     t <- mkReg (Next (fromInteger i))
     return t
 
-initTagEmpty :: Integer -> Module(Reg (Tag a))
-initTagEmpty i = do
-    t :: Reg (Tag a)
-    t <- mkReg Empty
+initTagTail :: Module(Reg (Tag numTags))
+initTagTail = do
+    t :: Reg (Tag numTags)
+    t <- mkReg Tail
     return t
 
 interface (TagEngine :: # -> *) numTags =
@@ -27,11 +27,23 @@ interface (TagEngine :: # -> *) numTags =
     retireTag  :: UIntLog2N(numTags) -> Action
 
 
+initTagVec :: Module(Vector numTags (Reg (Tag numTags)))
+initTagVec = 
+    do
+        tagVecSequential :: Vector numTags (Reg (Tag numTags))
+        tagVecSequential <- mapM (\idx -> initTagNext (idx+1)) genVector
+        let idxLast :: Integer = (fromInteger |> valueOf numTags) - 1
+        tailTag <- initTagTail
+        -- the tail of our TagVec should be `Tail` not `Next`
+        let finalTagVec = update tagVecSequential idxLast tailTag
+        return finalTagVec
+
 mkTagEngine :: Module (TagEngine numTags)
 mkTagEngine =
     do
-        let v :: Vector numTags Integer = genVector
-        -- placeholder
+        tagVec :: Vector numTags (Reg (Tag numTags))
+        tagVec <- initTagVec
+
         counter <- mkReg(0 :: UIntLog2N(numTags))
         return $
           interface TagEngine
@@ -46,6 +58,7 @@ mkTagEngine =
                 counter := 0
     where
         a = "Hello"
+        idx_last :: Integer = (fromInteger |> valueOf numTags) - 1
 
 a :: Integer
 a = 3