diff --git a/include/xo/alloc/Forwarding1.hpp b/include/xo/alloc/Forwarding1.hpp
index 88ca849a..8999849a 100644
--- a/include/xo/alloc/Forwarding1.hpp
+++ b/include/xo/alloc/Forwarding1.hpp
@@ -32,7 +32,7 @@ namespace xo {
             /** required by Object i/face, but never called on Forwarding1 **/
             virtual Object *    _shallow_copy(gc::IAlloc * mm) const final override;
             /** required by Object i/face, but never called on Forwarding1 **/
-            virtual std::size_t _forward_children(gc::GC * mm) final override;
+            virtual std::size_t _forward_children(gc::IAlloc * mm) final override;
 
         private:
             /** the object that used to be located at this address (i.e. @c this)
diff --git a/include/xo/alloc/Object.hpp b/include/xo/alloc/Object.hpp
index f1d03225..f16dd6ac 100644
--- a/include/xo/alloc/Object.hpp
+++ b/include/xo/alloc/Object.hpp
@@ -119,17 +119,17 @@ namespace xo {
          *  @p src.        source object to be forwarded
          *  @p gc.         garbage collector
          */
-        static Object * _forward(Object * src, gc::GC * gc);
+        static Object * _forward(Object * src, gc::IAlloc * gc);
 
         template <typename T>
-        static void _forward_inplace(T ** src_addr, gc::GC * gc) {
+        static void _forward_inplace(T ** src_addr, gc::IAlloc * gc) {
             Object * fwd = _forward(*src_addr, gc);
 
             *src_addr = reinterpret_cast<T *>(fwd);
         }
 
         template <typename T>
-        static void _forward_inplace(gp<T> & src, gc::GC * gc) {
+        static void _forward_inplace(gp<T> & src, gc::IAlloc * gc) {
             _forward_inplace<T>(src.ptr_address(), gc);
         }
 
@@ -243,7 +243,7 @@ namespace xo {
          *  allocated by @ref _shallow_move
          *
          **/
-        virtual std::size_t _forward_children(gc::GC * gc) = 0;
+        virtual std::size_t _forward_children(gc::IAlloc * gc) = 0;
     };
 
     template <typename T>
diff --git a/src/alloc/Forwarding1.cpp b/src/alloc/Forwarding1.cpp
index 2cc183d5..f94bf4f1 100644
--- a/src/alloc/Forwarding1.cpp
+++ b/src/alloc/Forwarding1.cpp
@@ -60,7 +60,7 @@ namespace xo {
 
         // LCOV_EXCL_START
         std::size_t
-        Forwarding1::_forward_children(gc::GC *) {
+        Forwarding1::_forward_children(gc::IAlloc *) {
             assert(false);
             return 0;
         }
diff --git a/src/alloc/Object.cpp b/src/alloc/Object.cpp
index 560f941b..dbb86ae2 100644
--- a/src/alloc/Object.cpp
+++ b/src/alloc/Object.cpp
@@ -24,7 +24,7 @@ namespace xo {
     Object::mm = nullptr;
 
     Object *
-    Object::_forward(Object * src, gc::GC * gc)
+    Object::_forward(Object * src, gc::IAlloc * gc)
     {
         if (!src)
             return src;
diff --git a/utest/Forwarding1.test.cpp b/utest/Forwarding1.test.cpp
index 2dcb5efe..19d9bf1e 100644
--- a/utest/Forwarding1.test.cpp
+++ b/utest/Forwarding1.test.cpp
@@ -34,7 +34,7 @@ namespace xo {
 
                 virtual std::size_t _shallow_size() const final override { return sizeof(*this); }
                 virtual Object * _shallow_copy(gc::IAlloc * mm) const final override { return new (Cpof(mm, this)) DummyObject(*this); }
-                virtual std::size_t _forward_children(gc::GC * gc) final override { return _shallow_size(); }
+                virtual std::size_t _forward_children(gc::IAlloc * gc) final override { return _shallow_size(); }
 
             private:
                 std::array<char, 128> data_;