diff --git a/src/Expr.h b/src/Expr.h
index cb1644404b..d0560942e1 100644
--- a/src/Expr.h
+++ b/src/Expr.h
@@ -752,7 +752,7 @@ public:
 
 	// Optimization-related:
 	ExprPtr Duplicate() override;
-	bool WillTransform(Reducer* c) const override	{ return true; }
+	bool WillTransform(Reducer* c) const override;
 	bool WillTransformInConditional(Reducer* c) const override;
 	ExprPtr Reduce(Reducer* c, StmtPtr& red_stmt) override;
 
diff --git a/src/script_opt/Expr.cc b/src/script_opt/Expr.cc
index f347006762..6a55a57112 100644
--- a/src/script_opt/Expr.cc
+++ b/src/script_opt/Expr.cc
@@ -1054,9 +1054,20 @@ ExprPtr BoolExpr::Duplicate()
 	return SetSucc(new BoolExpr(tag, op1_d, op2_d));
 	}
 
+bool BoolExpr::WillTransform(Reducer* c) const
+	{
+	if ( op1->IsConst() || (op1->HasNoSideEffects() && op2->IsConst()) )
+		return true;
+
+	if ( IsVector(op1->GetType()->Tag()) )
+		return false;
+
+	return WillTransformInConditional(c);
+	}
+
 bool BoolExpr::WillTransformInConditional(Reducer* c) const
 	{
-	IDPtr common_id = nullptr;
+	IDPtr common_id;
 	std::vector<ConstExprPtr> patterns;
 
 	ExprPtr e_ptr = {NewRef{}, (Expr*) this};
@@ -1119,6 +1130,14 @@ ExprPtr BoolExpr::Reduce(Reducer* c, StmtPtr& red_stmt)
 			}
 		}
 
+	if ( IsVector(op1->GetType()->Tag()) )
+		{
+		if ( c->Optimizing() )
+			return ThisPtr();
+		else
+			return AssignToTemporary(c, red_stmt);
+		}
+
 	auto else_val = is_and ? val_mgr->False() : val_mgr->True();
 	ExprPtr else_e = make_intrusive<ConstExpr>(else_val);