diff --git a/dtool/src/cppparser/cppBison.yxx b/dtool/src/cppparser/cppBison.yxx
index 7a9797148e..f9a2c2ab9b 100644
--- a/dtool/src/cppparser/cppBison.yxx
+++ b/dtool/src/cppparser/cppBison.yxx
@@ -3278,17 +3278,9 @@ no_angle_bracket_const_expr:
 {
   $$ = new CPPExpression(CPPExpression::sizeof_func($3));
 }
-        | KW_SIZEOF '(' IDENTIFIER ')' %prec UNARY
+        | KW_SIZEOF no_angle_bracket_const_expr %prec UNARY
 {
-  CPPDeclaration *arg = $3->find_symbol(current_scope, global_scope, current_lexer);
-  if (arg == nullptr) {
-    yyerror("undefined sizeof argument: " + $3->get_fully_scoped_name(), @3);
-  } else if (arg->get_subtype() == CPPDeclaration::ST_instance) {
-    CPPInstance *inst = arg->as_instance();
-    $$ = new CPPExpression(CPPExpression::sizeof_func(inst->_type));
-  } else {
-    $$ = new CPPExpression(CPPExpression::sizeof_func(arg->as_type()));
-  }
+  $$ = new CPPExpression(CPPExpression::sizeof_func($2));
 }
         | KW_SIZEOF ELLIPSIS '(' name ')' %prec UNARY
 {
@@ -3402,9 +3394,9 @@ no_angle_bracket_const_expr:
 {
   $$ = new CPPExpression('f', $1);
 }
-        | no_angle_bracket_const_expr '.' no_angle_bracket_const_expr
+        | no_angle_bracket_const_expr '.' name
 {
-  $$ = new CPPExpression('.', $1, $3);
+  $$ = new CPPExpression('.', $1, new CPPExpression($3, current_scope, global_scope, current_lexer));
 }
         | no_angle_bracket_const_expr POINTSAT no_angle_bracket_const_expr
 {
@@ -3542,17 +3534,9 @@ const_expr:
 {
   $$ = new CPPExpression(CPPExpression::sizeof_func($3));
 }
-        | KW_SIZEOF '(' IDENTIFIER ')' %prec UNARY
+        | KW_SIZEOF const_expr %prec UNARY
 {
-  CPPDeclaration *arg = $3->find_symbol(current_scope, global_scope, current_lexer);
-  if (arg == nullptr) {
-    yyerror("undefined sizeof argument: " + $3->get_fully_scoped_name(), @3);
-  } else if (arg->get_subtype() == CPPDeclaration::ST_instance) {
-    CPPInstance *inst = arg->as_instance();
-    $$ = new CPPExpression(CPPExpression::sizeof_func(inst->_type));
-  } else {
-    $$ = new CPPExpression(CPPExpression::sizeof_func(arg->as_type()));
-  }
+  $$ = new CPPExpression(CPPExpression::sizeof_func($2));
 }
         | KW_SIZEOF ELLIPSIS '(' name ')' %prec UNARY
 {
@@ -3704,9 +3688,9 @@ const_expr:
 {
   $$ = new CPPExpression('f', $1);
 }
-        | const_expr '.' const_expr
+        | const_expr '.' name
 {
-  $$ = new CPPExpression('.', $1, $3);
+  $$ = new CPPExpression('.', $1, new CPPExpression($3, current_scope, global_scope, current_lexer));
 }
         | const_expr POINTSAT const_expr
 {
@@ -3886,17 +3870,9 @@ formal_const_expr:
 {
   $$ = new CPPExpression(CPPExpression::sizeof_func($3));
 }
-        | KW_SIZEOF '(' IDENTIFIER ')' %prec UNARY
+        | KW_SIZEOF formal_const_expr %prec UNARY
 {
-  CPPDeclaration *arg = $3->find_symbol(current_scope, global_scope, current_lexer);
-  if (arg == nullptr) {
-    yyerror("undefined sizeof argument: " + $3->get_fully_scoped_name(), @3);
-  } else if (arg->get_subtype() == CPPDeclaration::ST_instance) {
-    CPPInstance *inst = arg->as_instance();
-    $$ = new CPPExpression(CPPExpression::sizeof_func(inst->_type));
-  } else {
-    $$ = new CPPExpression(CPPExpression::sizeof_func(arg->as_type()));
-  }
+  $$ = new CPPExpression(CPPExpression::sizeof_func($2));
 }
         | KW_SIZEOF ELLIPSIS '(' name ')' %prec UNARY
 {
@@ -4044,9 +4020,9 @@ formal_const_expr:
 {
   $$ = new CPPExpression('f', $1);
 }
-        | formal_const_expr '.' const_expr
+        | formal_const_expr '.' name
 {
-  $$ = new CPPExpression('.', $1, $3);
+  $$ = new CPPExpression('.', $1, new CPPExpression($3, current_scope, global_scope, current_lexer));
 }
         | formal_const_expr POINTSAT const_expr
 {
diff --git a/dtool/src/cppparser/cppExpression.cxx b/dtool/src/cppparser/cppExpression.cxx
index 78da68b5a7..2ded01f836 100644
--- a/dtool/src/cppparser/cppExpression.cxx
+++ b/dtool/src/cppparser/cppExpression.cxx
@@ -429,12 +429,24 @@ type_trait(int trait, CPPType *type, CPPType *arg) {
 CPPExpression CPPExpression::
 sizeof_func(CPPType *type) {
   CPPExpression expr(0);
-  expr._type = T_sizeof;
+  expr._type = T_sizeof_type;
   expr._u._typecast._to = type;
   expr._u._typecast._op1 = nullptr;
   return expr;
 }
 
+/**
+ *
+ */
+CPPExpression CPPExpression::
+sizeof_func(CPPExpression *op1) {
+  CPPExpression expr(0);
+  expr._type = T_sizeof_expr;
+  expr._u._typecast._to = nullptr;
+  expr._u._typecast._op1 = op1;
+  return expr;
+}
+
 /**
  *
  */
@@ -629,7 +641,8 @@ evaluate() const {
   case T_empty_aggregate_init:
   case T_new:
   case T_default_new:
-  case T_sizeof:
+  case T_sizeof_type:
+  case T_sizeof_expr:
   case T_sizeof_ellipsis:
     return Result();
 
@@ -1058,7 +1071,8 @@ determine_type() const {
   case T_default_new:
     return CPPType::new_type(new CPPPointerType(_u._typecast._to));
 
-  case T_sizeof:
+  case T_sizeof_type:
+  case T_sizeof_expr:
   case T_sizeof_ellipsis:
   case T_alignof:
     // Note: this should actually be size_t, but that is defined as a typedef
@@ -1334,10 +1348,13 @@ is_fully_specified() const {
   case T_default_construct:
   case T_empty_aggregate_init:
   case T_default_new:
-  case T_sizeof:
+  case T_sizeof_type:
   case T_alignof:
     return _u._typecast._to->is_fully_specified();
 
+  case T_sizeof_expr:
+    return _u._typecast._op1->is_fully_specified();
+
   case T_sizeof_ellipsis:
     return _u._ident->is_fully_specified();
 
@@ -1469,7 +1486,7 @@ substitute_decl(CPPDeclaration::SubstDecl &subst,
   case T_default_construct:
   case T_empty_aggregate_init:
   case T_default_new:
-  case T_sizeof:
+  case T_sizeof_type:
   case T_alignof:
     rep->_u._typecast._to =
       _u._typecast._to->substitute_decl(subst, current_scope, global_scope)
@@ -1477,6 +1494,13 @@ substitute_decl(CPPDeclaration::SubstDecl &subst,
     any_changed = any_changed || (rep->_u._typecast._to != _u._typecast._to);
     break;
 
+  case T_sizeof_expr:
+    rep->_u._typecast._op1 =
+      _u._typecast._op1->substitute_decl(subst, current_scope, global_scope)
+      ->as_expression();
+    any_changed = any_changed || (rep->_u._typecast._op1 != _u._typecast._op1);
+    break;
+
   case T_trinary_operation:
     rep->_u._op._op3 =
       _u._op._op3->substitute_decl(subst, current_scope, global_scope)
@@ -1567,10 +1591,13 @@ is_tbd() const {
   case T_new:
   case T_default_construct:
   case T_default_new:
-  case T_sizeof:
+  case T_sizeof_type:
   case T_alignof:
     return _u._typecast._to->is_tbd();
 
+  case T_sizeof_expr:
+    return _u._typecast._op1->is_tbd();
+
   case T_trinary_operation:
     if (_u._op._op3->is_tbd()) {
       return true;
@@ -1807,12 +1834,17 @@ output(std::ostream &out, int indent_level, CPPScope *scope, bool) const {
     out << "())";
     break;
 
-  case T_sizeof:
+  case T_sizeof_type:
     out << "sizeof(";
     _u._typecast._to->output(out, indent_level, scope, false);
     out << ")";
     break;
 
+  case T_sizeof_expr:
+    out << "sizeof ";
+    _u._typecast._op1->output(out, indent_level, scope, false);
+    break;
+
   case T_sizeof_ellipsis:
     out << "sizeof...(";
     _u._ident->output(out, scope);
@@ -2222,10 +2254,13 @@ is_equal(const CPPDeclaration *other) const {
   case T_default_construct:
   case T_empty_aggregate_init:
   case T_default_new:
-  case T_sizeof:
+  case T_sizeof_type:
   case T_alignof:
     return _u._typecast._to == ot->_u._typecast._to;
 
+  case T_sizeof_expr:
+    return _u._typecast._op1 == ot->_u._typecast._op1;
+
   case T_unary_operation:
     return *_u._op._op1 == *ot->_u._op._op1;
 
@@ -2324,10 +2359,13 @@ is_less(const CPPDeclaration *other) const {
   case T_default_construct:
   case T_empty_aggregate_init:
   case T_default_new:
-  case T_sizeof:
+  case T_sizeof_type:
   case T_alignof:
     return _u._typecast._to < ot->_u._typecast._to;
 
+  case T_sizeof_expr:
+    return _u._typecast._op1 < ot->_u._typecast._op1;
+
   case T_trinary_operation:
     if (*_u._op._op3 != *ot->_u._op._op3) {
       return *_u._op._op3 < *ot->_u._op._op3;
diff --git a/dtool/src/cppparser/cppExpression.h b/dtool/src/cppparser/cppExpression.h
index 3cea871679..cd6030f73d 100644
--- a/dtool/src/cppparser/cppExpression.h
+++ b/dtool/src/cppparser/cppExpression.h
@@ -52,7 +52,8 @@ public:
     T_empty_aggregate_init,
     T_new,
     T_default_new,
-    T_sizeof,
+    T_sizeof_type,
+    T_sizeof_expr,
     T_sizeof_ellipsis,
     T_alignof,
     T_unary_operation,
@@ -89,6 +90,7 @@ public:
   static CPPExpression typeid_op(CPPExpression *op1, CPPType *std_type_info);
   static CPPExpression type_trait(int trait, CPPType *type, CPPType *arg = nullptr);
   static CPPExpression sizeof_func(CPPType *type);
+  static CPPExpression sizeof_func(CPPExpression *op1);
   static CPPExpression sizeof_ellipsis_func(CPPIdentifier *ident);
   static CPPExpression alignof_func(CPPType *type);
   static CPPExpression lambda(CPPClosureType *type);