diff --git a/include/pocketpy/codeobject.h b/include/pocketpy/codeobject.h
index bb37c1eb..736bb8ec 100644
--- a/include/pocketpy/codeobject.h
+++ b/include/pocketpy/codeobject.h
@@ -71,7 +71,7 @@ struct CodeObject {
     std::vector<int> iblocks;       // block index for each bytecode
     std::vector<LineInfo> lines;
     
-    small_vector<PyObject*, 6> consts;
+    small_vector<PyObject*, 8> consts;
     small_vector<StrName, 16> varnames;      // local variables
     NameDictInt varnames_inv;
     small_vector<CodeBlock, 4> blocks;
diff --git a/include/pocketpy/expr.h b/include/pocketpy/expr.h
index cc0a28f1..5cd06956 100644
--- a/include/pocketpy/expr.h
+++ b/include/pocketpy/expr.h
@@ -51,7 +51,7 @@ public:
 };
 
 typedef unique_ptr_128<Expr> Expr_;
-typedef small_vector<Expr_, 6> Expr_vector;
+typedef small_vector<Expr_, 4> Expr_vector;
 
 template<>
 struct TriviallyRelocatable<Expr_>{