diff --git a/src/script_opt/Expr.cc b/src/script_opt/Expr.cc
index 95f2274150..8cc45b654f 100644
--- a/src/script_opt/Expr.cc
+++ b/src/script_opt/Expr.cc
@@ -881,40 +881,77 @@ ExprPtr AddToExpr::Duplicate()
 	return SetSucc(new AddToExpr(op1_d, op2_d));
 	}
 
+bool AddToExpr::IsReduced(Reducer* c) const
+	{
+	auto t = op1->GetType();
+	auto tag = t->Tag();
+
+	if ( tag == TYPE_PATTERN )
+		return op1->HasReducedOps(c) && op2->IsReduced(c);
+
+	if ( tag == TYPE_TABLE )
+		return op1->IsReduced(c) && op2->IsReduced(c);
+
+	if ( tag == TYPE_VECTOR && same_type(t, op2->GetType()) )
+		return op1->IsReduced(c) && op2->IsReduced(c);
+
+	return NonReduced(this);
+	}
+
 ExprPtr AddToExpr::Reduce(Reducer* c, StmtPtr& red_stmt)
 	{
-	if ( IsVector(op1->GetType()->Tag()) )
+	auto tag = op1->GetType()->Tag();
+
+	switch ( tag )
 		{
-		StmtPtr red_stmt1;
-		StmtPtr red_stmt2;
+		case TYPE_PATTERN:
+		case TYPE_TABLE:
+		case TYPE_VECTOR:
+			{
+			StmtPtr red_stmt1;
+			StmtPtr red_stmt2;
 
-		if ( op1->Tag() == EXPR_FIELD )
-			red_stmt1 = op1->ReduceToSingletons(c);
-		else
-			op1 = op1->Reduce(c, red_stmt1);
+			if ( tag == TYPE_PATTERN && op1->Tag() == EXPR_FIELD )
+				red_stmt1 = op1->ReduceToSingletons(c);
+			else
+				op1 = op1->Reduce(c, red_stmt1);
 
-		op2 = op2->Reduce(c, red_stmt2);
+			auto& t = op1->GetType();
+			op2 = op2->Reduce(c, red_stmt2);
 
-		auto append = make_intrusive<AppendToExpr>(op1->Duplicate(), op2);
-		append->SetOriginal(ThisPtr());
+			red_stmt = MergeStmts(red_stmt1, red_stmt2);
 
-		auto append_stmt = make_intrusive<ExprStmt>(append);
+			if ( tag == TYPE_VECTOR && ! same_type(t, op2->GetType()) )
+				{
+				auto append = make_intrusive<AppendToExpr>(op1->Duplicate(), op2);
+				append->SetOriginal(ThisPtr());
 
-		red_stmt = MergeStmts(red_stmt1, red_stmt2, append_stmt);
+				auto append_stmt = make_intrusive<ExprStmt>(append);
 
-		return op1;
+				red_stmt = MergeStmts(red_stmt, append_stmt);
+
+				return op1;
+				}
+
+			return ThisPtr();
+			}
+
+		default:
+			{
+			auto rhs = op1->AsRefExprPtr()->GetOp1();
+			auto do_incr = make_intrusive<AddExpr>(rhs->Duplicate(), op2);
+			auto assign = make_intrusive<AssignExpr>(op1, do_incr, false, nullptr, nullptr, false);
+
+			return assign->ReduceToSingleton(c, red_stmt);
+			}
 		}
+	}
 
-	else
-		{
-		// We could do an ASSERT that op1 is an EXPR_REF, but
-		// the following is basically equivalent.
-		auto rhs = op1->AsRefExprPtr()->GetOp1();
-		auto do_incr = make_intrusive<AddExpr>(rhs->Duplicate(), op2);
-		auto assign = make_intrusive<AssignExpr>(op1, do_incr, false, nullptr, nullptr, false);
-
-		return assign->ReduceToSingleton(c, red_stmt);
-		}
+ExprPtr AddToExpr::ReduceToSingleton(Reducer* c, StmtPtr& red_stmt)
+	{
+	auto at_stmt = make_intrusive<ExprStmt>(Duplicate());
+	red_stmt = at_stmt->Reduce(c);
+	return op1;
 	}
 
 ExprPtr SubExpr::Duplicate()
@@ -972,15 +1009,43 @@ ExprPtr RemoveFromExpr::Duplicate()
 	return SetSucc(new RemoveFromExpr(op1_d, op2_d));
 	}
 
+bool RemoveFromExpr::IsReduced(Reducer* c) const
+	{
+	if ( op1->GetType()->Tag() == TYPE_TABLE )
+		return op1->IsReduced(c) && op2->IsReduced(c);
+
+	return NonReduced(this);
+	}
+
 ExprPtr RemoveFromExpr::Reduce(Reducer* c, StmtPtr& red_stmt)
 	{
-	auto rhs = op1->AsRefExprPtr()->GetOp1();
-	auto do_decr = make_intrusive<SubExpr>(rhs->Duplicate(), op2);
+	if ( op1->GetType()->Tag() == TYPE_TABLE )
+		{
+		StmtPtr red_stmt1;
+		StmtPtr red_stmt2;
+
+		op1 = op1->Reduce(c, red_stmt1);
+		op2 = op2->Reduce(c, red_stmt2);
+
+		red_stmt = MergeStmts(red_stmt1, red_stmt2);
+
+		return ThisPtr();
+		}
+
+	auto lhs = op1->AsRefExprPtr()->GetOp1();
+	auto do_decr = make_intrusive<SubExpr>(lhs->Duplicate(), op2);
 	auto assign = make_intrusive<AssignExpr>(op1, do_decr, false, nullptr, nullptr, false);
 
 	return assign->Reduce(c, red_stmt);
 	}
 
+ExprPtr RemoveFromExpr::ReduceToSingleton(Reducer* c, StmtPtr& red_stmt)
+	{
+	auto rf_stmt = make_intrusive<ExprStmt>(Duplicate());
+	red_stmt = rf_stmt->Reduce(c);
+	return op1;
+	}
+
 ExprPtr TimesExpr::Duplicate()
 	{
 	auto op1_d = op1->Duplicate();
@@ -2676,6 +2741,13 @@ ExprPtr AppendToExpr::Reduce(Reducer* c, StmtPtr& red_stmt)
 	return ThisPtr();
 	}
 
+ExprPtr AppendToExpr::ReduceToSingleton(Reducer* c, StmtPtr& red_stmt)
+	{
+	auto at_stmt = make_intrusive<ExprStmt>(Duplicate());
+	red_stmt = at_stmt->Reduce(c);
+	return op1->AsRefExprPtr()->GetOp1();
+	}
+
 IndexAssignExpr::IndexAssignExpr(ExprPtr arg_op1, ExprPtr arg_op2, ExprPtr arg_op3)
 	: BinaryExpr(EXPR_INDEX_ASSIGN, std::move(arg_op1), std::move(arg_op2))
 	{
diff --git a/src/script_opt/Stmt.cc b/src/script_opt/Stmt.cc
index feea66a927..8251e05c71 100644
--- a/src/script_opt/Stmt.cc
+++ b/src/script_opt/Stmt.cc
@@ -161,7 +161,8 @@ StmtPtr ExprStmt::DoReduce(Reducer* c)
 		return TransformMe(make_intrusive<NullStmt>(), c);
 
 	if ( (t == EXPR_ASSIGN || t == EXPR_CALL || t == EXPR_INDEX_ASSIGN ||
-	      t == EXPR_FIELD_LHS_ASSIGN || t == EXPR_APPEND_TO) &&
+	      t == EXPR_FIELD_LHS_ASSIGN || t == EXPR_APPEND_TO || t == EXPR_ADD_TO ||
+	      t == EXPR_REMOVE_FROM) &&
 	     e->IsReduced(c) )
 		return ThisPtr();
 
diff --git a/src/script_opt/UseDefs.cc b/src/script_opt/UseDefs.cc
index de204cc558..21ebb59548 100644
--- a/src/script_opt/UseDefs.cc
+++ b/src/script_opt/UseDefs.cc
@@ -466,6 +466,15 @@ UDs UseDefs::ExprUDs(const Expr* e)
 			AddInExprUDs(uds, e->GetOp1()->AsRefExprPtr()->GetOp1().get());
 			break;
 
+		case EXPR_ADD_TO:
+		case EXPR_REMOVE_FROM:
+			{
+			AddInExprUDs(uds, e->GetOp1().get());
+			auto rhs_UDs = ExprUDs(e->GetOp2().get());
+			uds = UD_Union(uds, rhs_UDs);
+			break;
+			}
+
 		case EXPR_RECORD_CONSTRUCTOR:
 			{
 			auto r = static_cast<const RecordConstructorExpr*>(e);
@@ -527,6 +536,10 @@ void UseDefs::AddInExprUDs(UDs uds, const Expr* e)
 	{
 	switch ( e->Tag() )
 		{
+		case EXPR_REF:
+			AddInExprUDs(uds, e->GetOp1().get());
+			break;
+
 		case EXPR_NAME:
 			AddID(uds, e->AsNameExpr()->Id());
 			break;
@@ -548,8 +561,9 @@ void UseDefs::AddInExprUDs(UDs uds, const Expr* e)
 			AddInExprUDs(uds, e->GetOp1()->AsRefExprPtr()->GetOp1().get());
 			break;
 
-		case EXPR_ASSIGN:
-			// These occur inside of table constructors.
+		case EXPR_ASSIGN: // can occur inside a table constructor
+		case EXPR_ADD_TO:
+		case EXPR_REMOVE_FROM:
 			AddInExprUDs(uds, e->GetOp1().get());
 			AddInExprUDs(uds, e->GetOp2().get());
 			break;