diff --git a/dep/ggpo-x/include/ggponet.h b/dep/ggpo-x/include/ggponet.h
index 1f99e917a..96ce61500 100644
--- a/dep/ggpo-x/include/ggponet.h
+++ b/dep/ggpo-x/include/ggponet.h
@@ -231,6 +231,12 @@ typedef struct {
     */
    bool (__cdecl *load_game_state)(void* context, unsigned char* buffer, int len, int framesToRollback, int frameToLoad);
 
+   /*
+    * copy_game_state - creates a copy of an existing save state.
+    */
+   bool(__cdecl* copy_game_state)(void* context, unsigned char** out_buffer, int* out_len, int* out_checksum,
+                                  const unsigned char* in_buffer, const int in_len, const int in_checksum);
+
    /*
     * log_game_state - Used in diagnostic testing.  The client should use
     * the ggpo_log function to write the contents of the specified save
diff --git a/dep/ggpo-x/src/backends/synctest.cpp b/dep/ggpo-x/src/backends/synctest.cpp
index 692bab4d8..c82a9c60d 100644
--- a/dep/ggpo-x/src/backends/synctest.cpp
+++ b/dep/ggpo-x/src/backends/synctest.cpp
@@ -126,9 +126,12 @@ SyncTestBackend::IncrementFrame(uint16_t cs)
    SavedInfo info;
    info.frame = frame;
    info.input = _last_input;
-   info.cbuf = _sync.GetLastSavedFrame().cbuf;
-   info.buf = (char *)malloc(info.cbuf);
-   memcpy(info.buf, _sync.GetLastSavedFrame().buf, info.cbuf);
+
+   const Sync::SavedFrame& lsf = _sync.GetLastSavedFrame();
+   info.cbuf = 0;
+   info.buf = nullptr;
+   info.checksum = 0;
+   _callbacks.copy_game_state(_callbacks.context, &info.buf, &info.cbuf, &info.checksum, lsf.buf, lsf.cbuf, lsf.checksum);
    info.checksum = _sync.GetLastSavedFrame().checksum;
    _saved_frames.push(info);
 
@@ -155,7 +158,7 @@ SyncTestBackend::IncrementFrame(uint16_t cs)
             RaiseSyncError("Checksum for frame %d does not match saved (%d != %d)", frame, checksum, info.checksum);
          }
          printf("Checksum %08d for frame %d matches.\n", checksum, info.frame);
-         free(info.buf);
+         _callbacks.free_buffer(_callbacks.context, info.buf);
       }
       _last_verified = frame;
       _rollingback = false;
diff --git a/dep/ggpo-x/src/backends/synctest.h b/dep/ggpo-x/src/backends/synctest.h
index f0955a35f..924dbfb27 100644
--- a/dep/ggpo-x/src/backends/synctest.h
+++ b/dep/ggpo-x/src/backends/synctest.h
@@ -31,7 +31,7 @@ protected:
    struct SavedInfo {
       int         frame;
       int         checksum;
-      char        *buf;
+      byte        *buf;
       int         cbuf;
       GameInput   input;
    };