diff --git a/thirdparty/detray/CMakeLists.txt b/thirdparty/detray/CMakeLists.txt
index 4f58b537601e..7274dcb68749 100644
--- a/thirdparty/detray/CMakeLists.txt
+++ b/thirdparty/detray/CMakeLists.txt
@@ -15,9 +15,7 @@ message( STATUS "Building Detray as part of the Acts project" )
 set( DETRAY_VERSION "v${_acts_detray_version}")
 
 # Declare where to get Detray from.
-FetchContent_Declare( -DDetray ${ACTS_DETRAY_SOURCE} )
-
-add_definitions( DETRAY_ALGEBRA_ARRAY )
+FetchContent_Declare( Detray ${ACTS_DETRAY_SOURCE} )
 
 # Options used in the build of Detray.
 set( DETRAY_CUSTOM_SCALARTYPE "float" CACHE STRING
diff --git a/thirdparty/traccc/CMakeLists.txt b/thirdparty/traccc/CMakeLists.txt
index ecd529613700..5e172d1a7cd2 100644
--- a/thirdparty/traccc/CMakeLists.txt
+++ b/thirdparty/traccc/CMakeLists.txt
@@ -8,44 +8,30 @@
 
 # CMake include(s).
 cmake_minimum_required(VERSION 3.14)
-include(FetchContent)
+include(ExternalProject)
 
 # Tell the user what's happening.
 message( STATUS "Building traccc as part of the Acts project" )
 
-set( TRACCC_VERSION "${_acts_traccc_version}")
+set(traccc_INCLUDE_DIR ${CMAKE_CURRENT_BINARY_DIR}/traccc-prefix/src/traccc)
+#set( TRACCC_VERSION "${_acts_traccc_version}")
 
-# Declare where to get traccc from.
-FetchContent_Declare( traccc ${ACTS_TRACCC_SOURCE} )
+set( TRACCC_SETUP_VECMEM OFF )
+set( TRACCC_SETUP_EIGEN3 OFF )
+set( TRACCC_SETUP_THRUST ON ) 
+set( TRACCC_SETUP_ALGEBRA_PLUGINS OFF ) 
+set( TRACCC_SETUP_COVFIE OFF ) 
+set( TRACCC_SETUP_DFELIBS OFF ) 
+set( TRACCC_SETUP_DETRAY OFF ) 
+set( TRACCC_SETUP_ACTS OFF ) 
+set( TRACCC_SETUP_TBB OFF ) 
 
-set( TRACCC_SETUP_VECMEM OFF CACHE BOOL
-   "Do not set up Actsvg as part of Traccc" )
-set( TRACCC_SETUP_EIGEN3 OFF CACHE BOOL
-   "Do not set up Eigen3 as part of Traccc" )
-set( TRACCC_SETUP_THRUST ON CACHE BOOL
-    "Do not set up Thrust as part of Traccc" ) 
-set( TRACCC_SETUP_ALGEBRA_PLUGINS OFF CACHE BOOL
-    "Do not set up Algebra Plugins as part of Traccc" ) 
-set( TRACCC_SETUP_COVFIE OFF CACHE BOOL
-    "Do not set up Covfie as part of Traccc" ) 
-set( TRACCC_SETUP_DFELIBS OFF CACHE BOOL
-    "Do not set up dfelibs as part of Traccc" ) 
-set( TRACCC_SETUP_DETRAY OFF CACHE BOOL
-    "Do not set up Detray as part of Traccc" ) 
-set( TRACCC_SETUP_ACTS OFF CACHE BOOL
-    "Do not set up ACTS as part of Traccc" ) 
-set( TRACCC_SETUP_TBB OFF CACHE BOOL
-    "Do not set up TBB as part of Traccc" ) 
+set( TRACCC_BUILD_TESTING OFF ) 
+set( TRACCC_BUILD_EXAMPLES OFF ) 
 
-set( TRACCC_BUILD_TESTING OFF CACHE BOOL
-    "Turn off the build of the Traccc unit tests" ) 
-set( TRACCC_BUILD_EXAMPLES OFF CACHE BOOL
-    "Turn off the build of the Traccc examples" ) 
-
-# Now set up its build.
-FetchContent_MakeAvailable( traccc )
+ExternalProject_Add( traccc "${ACTS_TRACCC_SOURCE};CONFIGURE_COMMAND;;BUILD_COMMAND;;INSTALL_COMMAND;" )
 
 add_library(traccc::traccc INTERFACE IMPORTED GLOBAL)
-add_dependencies(traccc::traccc traccc)
+add_dependencies(traccc::traccc traccc::core traccc::io)
 target_include_directories(traccc::traccc INTERFACE ${traccc_INCLUDE_DIR})
 install(DIRECTORY ${traccc_INCLUDE_DIR}/traccc DESTINATION ${CMAKE_INSTALL_INCLUDEDIR})
\ No newline at end of file