diff --git a/src/expression2/DConstant.cpp b/src/expression2/DConstant.cpp
index 420431bc..46d4cbe9 100644
--- a/src/expression2/DConstant.cpp
+++ b/src/expression2/DConstant.cpp
@@ -80,7 +80,7 @@ namespace xo {
         DConstant *
         DConstant::shallow_move(obj<ACollector> gc) noexcept
         {
-            return gc.std_copy_for(this);
+            return gc.std_move_for(this);
         }
 
         std::size_t
diff --git a/src/expression2/DDefineExpr.cpp b/src/expression2/DDefineExpr.cpp
index e324b528..b25a655d 100644
--- a/src/expression2/DDefineExpr.cpp
+++ b/src/expression2/DDefineExpr.cpp
@@ -87,7 +87,7 @@ namespace xo {
         DDefineExpr *
         DDefineExpr::shallow_move(obj<ACollector> gc) noexcept
         {
-            return gc.std_copy_for(this);
+            return gc.std_move_for(this);
         }
 
         std::size_t
diff --git a/src/expression2/DGlobalSymtab.cpp b/src/expression2/DGlobalSymtab.cpp
index 8d0f74cf..58275e54 100644
--- a/src/expression2/DGlobalSymtab.cpp
+++ b/src/expression2/DGlobalSymtab.cpp
@@ -263,7 +263,7 @@ namespace xo {
         DGlobalSymtab *
         DGlobalSymtab::shallow_move(obj<ACollector> gc) noexcept
         {
-            return gc.std_copy_for(this);
+            return gc.std_move_for(this);
         }
 
         std::size_t
diff --git a/src/expression2/DIfElseExpr.cpp b/src/expression2/DIfElseExpr.cpp
index 3fb71682..81efee1e 100644
--- a/src/expression2/DIfElseExpr.cpp
+++ b/src/expression2/DIfElseExpr.cpp
@@ -91,7 +91,7 @@ namespace xo {
         DIfElseExpr *
         DIfElseExpr::shallow_move(obj<ACollector> gc) noexcept
         {
-            return gc.std_copy_for(this);
+            return gc.std_move_for(this);
         }
 
         std::size_t
diff --git a/src/expression2/DLambdaExpr.cpp b/src/expression2/DLambdaExpr.cpp
index 4919840b..8069cd3c 100644
--- a/src/expression2/DLambdaExpr.cpp
+++ b/src/expression2/DLambdaExpr.cpp
@@ -141,7 +141,7 @@ namespace xo {
 
         DLambdaExpr *
         DLambdaExpr::shallow_move(obj<ACollector> gc) noexcept {
-            return gc.std_copy_for(this);
+            return gc.std_move_for(this);
         }
 
         std::size_t
diff --git a/src/expression2/DLocalSymtab.cpp b/src/expression2/DLocalSymtab.cpp
index d1c4930c..60cdd2e2 100644
--- a/src/expression2/DLocalSymtab.cpp
+++ b/src/expression2/DLocalSymtab.cpp
@@ -121,7 +121,7 @@ namespace xo {
         DLocalSymtab *
         DLocalSymtab::shallow_move(obj<ACollector> gc) noexcept
         {
-            return gc.std_copy_for(this);
+            return gc.std_move_for(this);
         }
 
         std::size_t
diff --git a/src/expression2/DSequenceExpr.cpp b/src/expression2/DSequenceExpr.cpp
index 33149785..ed03affc 100644
--- a/src/expression2/DSequenceExpr.cpp
+++ b/src/expression2/DSequenceExpr.cpp
@@ -122,7 +122,7 @@ namespace xo {
         DSequenceExpr *
         DSequenceExpr::shallow_move(obj<ACollector> gc) noexcept
         {
-            return gc.std_copy_for(this);
+            return gc.std_move_for(this);
         }
 
         std::size_t
diff --git a/src/expression2/DTypename.cpp b/src/expression2/DTypename.cpp
index 81509949..c9f56cf1 100644
--- a/src/expression2/DTypename.cpp
+++ b/src/expression2/DTypename.cpp
@@ -49,7 +49,7 @@ namespace xo {
         DTypename *
         DTypename::shallow_move(obj<ACollector> gc) noexcept
         {
-            return gc.std_copy_for(this);
+            return gc.std_move_for(this);
         }
 
         size_t
diff --git a/src/expression2/DVarRef.cpp b/src/expression2/DVarRef.cpp
index 186fa29a..3b9b2638 100644
--- a/src/expression2/DVarRef.cpp
+++ b/src/expression2/DVarRef.cpp
@@ -67,7 +67,7 @@ namespace xo {
         DVarRef *
         DVarRef::shallow_move(obj<ACollector> gc) noexcept
         {
-            return gc.std_copy_for(this);
+            return gc.std_move_for(this);
         }
 
         std::size_t
diff --git a/src/expression2/DVariable.cpp b/src/expression2/DVariable.cpp
index f11000aa..68a87f67 100644
--- a/src/expression2/DVariable.cpp
+++ b/src/expression2/DVariable.cpp
@@ -47,7 +47,7 @@ namespace xo {
         DVariable *
         DVariable::shallow_move(obj<ACollector> gc) noexcept
         {
-            return gc.std_copy_for(this);
+            return gc.std_move_for(this);
         }
 
         size_t