diff --git a/external/CMakeLists.txt b/external/CMakeLists.txt
index d0843683605e1ffeec46e52a02158a289405d0ab..0b6630140dc5cc089c24f76fefa4172a27895ec1 100644
--- a/external/CMakeLists.txt
+++ b/external/CMakeLists.txt
@@ -6,6 +6,11 @@
 # it off execept for the checker.
 Option(DOWNLOAD_EXTERNALS "Download the code from the external repositories." ON)
 
+Option(CBM_MCBM_PARS "Download mCBM forks for geometry and parameters" OFF)
+if (CBM_MCBM_PARS)
+  message(WARNING "MCBM PARS ENABLED: Using mcbm forks of parameters and geometry.")
+endif()
+
 if(DOWNLOAD_EXTERNALS)
   Include(InstallFlesnet.cmake)
   Set(FLES_IPC_INCLUDE_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/flesnet/lib/fles_ipc PARENT_SCOPE)
diff --git a/external/InstallGeometry.cmake b/external/InstallGeometry.cmake
index 9e54ad1962e4677db72ae3a1390f112b90e08674..4b34ef7f36e452ec5c523724becabffc8a81a213 100644
--- a/external/InstallGeometry.cmake
+++ b/external/InstallGeometry.cmake
@@ -1,7 +1,12 @@
 set(GEOMETRY_VERSION 4d9bfb87b3b8bf0adc298fa424976f8fbe9827db)
-
 set(GEOMETRY_SRC_URL "https://git.cbm.gsi.de/CbmSoft/cbmroot_geometry.git")
 
+if (CBM_MCBM_PARS)
+  # Override defaults to use mcbm fork instead
+  set(GEOMETRY_VERSION mcbm24_master)
+  set(GEOMETRY_SRC_URL https://git.cbm.gsi.de/mcbm/cbmroot_geometry.git)
+endif()
+
 download_project_if_needed(PROJECT         Geometry_source
                            GIT_REPOSITORY  ${GEOMETRY_SRC_URL}
                            GIT_TAG         ${GEOMETRY_VERSION}
diff --git a/external/InstallParameter.cmake b/external/InstallParameter.cmake
index 7a5f5942f6802fdf1cced3fce19dd84a116d6ba1..667fd9d949cc9127b782600342b912bbf4a8c623 100644
--- a/external/InstallParameter.cmake
+++ b/external/InstallParameter.cmake
@@ -2,6 +2,12 @@ set(PARAMETER_VERSION eef953885621eda9395f9c6e6e089bc3cd160c5e) # 2024-05-11
 
 set(PARAMETER_SRC_URL "https://git.cbm.gsi.de/CbmSoft/cbmroot_parameter.git")
 
+if (CBM_MCBM_PARS)
+  # Override defaults to use mcbm fork instead
+  set(PARAMETER_VERSION mcbm24_master)
+  set(PARAMETER_SRC_URL "https://git.cbm.gsi.de/mcbm/cbmroot_parameter.git")
+endif()
+
 download_project_if_needed(PROJECT         Parameter_source
                            GIT_REPOSITORY  ${PARAMETER_SRC_URL}
                            GIT_TAG         ${PARAMETER_VERSION}