diff --git a/rts/memory.c b/rts/memory.c
index e2b2628..c946605 100644
--- a/rts/memory.c
+++ b/rts/memory.c
@@ -77,6 +77,12 @@ void sixten_increase_reference_count(uintptr_t heap_object) {
   ++header->reference_count;
 }
 
+void sixten_increase_reference_counts(uintptr_t* data, uint32_t count) {
+  for (uint32_t i = 0; i < count; ++i) {
+    sixten_increase_reference_count(data[i]);
+  }
+}
+
 void sixten_decrease_reference_count(uintptr_t heap_object) {
   uint8_t* pointer = heap_object_pointer(heap_object);
   if (pointer == 0) {
diff --git a/rts/memory.h b/rts/memory.h
index 8bd7914..b5a4ec6 100644
--- a/rts/memory.h
+++ b/rts/memory.h
@@ -17,5 +17,6 @@ void sixten_copy(
   uint32_t non_pointer_bytes
 );
 void sixten_increase_reference_count(uintptr_t heap_object);
+void sixten_increase_reference_counts(uintptr_t* data, uint32_t count);
 void sixten_decrease_reference_count(uintptr_t heap_object);
 void sixten_decrease_reference_counts(uintptr_t* data, uint32_t count);
diff --git a/src/Lower.hs b/src/Lower.hs
index eacffe9..119f2db 100644
--- a/src/Lower.hs
+++ b/src/Lower.hs
@@ -187,7 +187,7 @@ definition name = \case
               seq_ $ Store (Global Representation.int initedName) (Literal $ Literal.Integer 1) Representation.int
               _ <- storeTerm CC.empty Index.Seq.Empty (Global repr (Name.Lowered name Name.Original)) term
               pure $ Undefined Representation.Empty
-            letValue Representation.Empty "case_result" $ Case inited [LiteralBranch (Literal.Integer 0) initBranch] $ Just $ Operand $ Undefined Representation.Empty
+            _ <- letValue Representation.Empty "case_result" $ Case inited [LiteralBranch (Literal.Integer 0) initBranch] $ Just $ Operand $ Undefined Representation.Empty
             pure $ Undefined Representation.Empty
           let init = readback Index.Map.Empty initValue
           pure
@@ -620,7 +620,7 @@ moduleInit moduleName definitions = do
       forM_ constantsToInitialize \defName ->
         letValue Representation.Empty "init-result" $ Call defName []
       pure $ Undefined Representation.Empty
-    letValue Representation.Empty "case-result" $ Case inited [LiteralBranch (Literal.Integer 0) initBranch] $ Just $ Operand $ Undefined Representation.Empty
+    _ <- letValue Representation.Empty "case-result" $ Case inited [LiteralBranch (Literal.Integer 0) initBranch] $ Just $ Operand $ Undefined Representation.Empty
     pure $ Undefined Representation.Empty
   let init = readback Index.Map.Empty initValue
   pure
diff --git a/src/ReferenceCounting.hs b/src/ReferenceCounting.hs
index 8afff13..cd118f5 100644
--- a/src/ReferenceCounting.hs
+++ b/src/ReferenceCounting.hs
@@ -251,8 +251,7 @@ referenceCount passBy value = case value of
             pure (Let passValBy name var dead val''' body'', Just $ Owned (PassBy.Value repr) 1)
       _ -> pure (Let passValBy name var dead val'' body', bodyProvenance)
   Seq lhs rhs -> do
-    (lhs', lhsProvenance) <- referenceCount (PassBy.Value mempty) lhs
-    when (isJust lhsProvenance) $ panic $ "Seq with provenance " <> show lhs'
+    (increaseBefores, decreaseAfters) <- referenceCountSeqOperation lhs
     (rhs', rhsProvenance) <- referenceCount passBy rhs
     pure (Seq lhs' rhs', rhsProvenance)
 
@@ -318,23 +317,23 @@ referenceCountLetOperation passBy operation = case operation of
     pure (operation, Child <$> maybeParent, maybeToList decreaseSrc)
 
 referenceCountSeqOperation
-  :: PassBy
-  -> SeqOperation
-  -> ReferenceCount ([(Var, Representation)], [(Var, Representation)])
-referenceCountSeqOperation passBy operation = case operation of
-  Copy dst src _ -> do
+  :: SeqOperation
+  -> ReferenceCount ([(Operand, Either Representation Operand)], [(Var, Representation)])
+referenceCountSeqOperation operation = case operation of
+  Copy dst src repr -> do
     decreaseDst <- referenceCountOperand dst
     decreaseSrc <- referenceCountOperand src
-    -- TODO
-    pure ([], catMaybes [decreaseDst decreaseSrc])
+    pure case (src, decreaseSrc) of
+      (Var Killed srcVar, Just (srcVar', _))
+        | srcVar == srcVar' -> ([], maybeToList decreaseDst)
+      _ -> ([(src, Right repr)], catMaybes [decreaseDst, decreaseSrc])
   Store dst src repr -> do
     decreaseDst <- referenceCountOperand dst
     decreaseSrc <- referenceCountOperand src
     pure case (src, decreaseSrc) of
       (Var Killed srcVar, Just (srcVar', _))
-        | srcVar == srcVar' ->
-            ([], maybeToList decreaseDst)
-      _ -> ([(src, repr)], catMaybes [decreaseDst, decreaseSrc])
+        | srcVar == srcVar' -> ([], maybeToList decreaseDst)
+      _ -> ([(src, Left repr)], catMaybes [decreaseDst, decreaseSrc])
   IncreaseReferenceCount {} -> panic "RC operations before reference counting"
   DecreaseReferenceCount {} -> panic "RC operations before reference counting"