diff --git a/tools/cmake/run_size_tool.cmake b/tools/cmake/run_size_tool.cmake
index 27be3977e7..5a53c9c221 100644
--- a/tools/cmake/run_size_tool.cmake
+++ b/tools/cmake/run_size_tool.cmake
@@ -32,6 +32,10 @@ if(DEFINED IDF_SIZE_MODE)
     list(APPEND IDF_SIZE_CMD ${IDF_SIZE_MODE})
 endif()
 
+if(DEFINED ENV{ESP_IDF_SIZE_NG})
+    list(APPEND IDF_SIZE_CMD "--unify")
+endif()
+
 list(APPEND IDF_SIZE_CMD ${MAP_FILE})
 
 execute_process(COMMAND ${IDF_SIZE_CMD}