diff --git a/cmake/modules/RootMacros.cmake b/cmake/modules/RootMacros.cmake
index 3ce1d5d5d1162..541613938efd6 100644
--- a/cmake/modules/RootMacros.cmake
+++ b/cmake/modules/RootMacros.cmake
@@ -2037,7 +2037,7 @@ function(ROOT_ADD_PYUNITTESTS name)
 
   string(REGEX REPLACE "[_]" "-" good_name "${name}")
   ROOT_ADD_TEST(pyunittests-${good_name}
-                COMMAND ${Python3_EXECUTABLE} -B -m unittest discover -s ${CMAKE_CURRENT_SOURCE_DIR} -p "*.py" -v
+                COMMAND ${Python3_EXECUTABLE_DEV} -B -m unittest discover -s ${CMAKE_CURRENT_SOURCE_DIR} -p "*.py" -v
                 ENVIRONMENT PYTHONPATH=${pythonpaths_native})
 endfunction()
 
@@ -2097,9 +2097,9 @@ function(ROOT_ADD_PYUNITTEST name file)
   string(REPLACE "-test-" "-" clean_name_with_path ${name_with_path})
 
   if(ARG_GENERIC)
-    set(test_cmd COMMAND ${Python3_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/${file_name})
+    set(test_cmd COMMAND ${Python3_EXECUTABLE_DEV} ${CMAKE_CURRENT_SOURCE_DIR}/${file_name})
   else()
-    set(test_cmd COMMAND ${Python3_EXECUTABLE} -B -m unittest discover -s ${CMAKE_CURRENT_SOURCE_DIR}/${file_dir} -p ${file_name} -v)
+    set(test_cmd COMMAND ${Python3_EXECUTABLE_DEV} -B -m unittest discover -s ${CMAKE_CURRENT_SOURCE_DIR}/${file_dir} -p ${file_name} -v)
   endif()
 
   set(test_name pyunittests${clean_name_with_path})
@@ -3026,7 +3026,7 @@ macro(ROOTTEST_SETUP_MACROTEST)
   # Add python script to CTest.
   elseif(ARG_MACRO MATCHES "[.]py")
     get_filename_component(realfp ${ARG_MACRO} REALPATH)
-    set(command ${Python3_EXECUTABLE} ${realfp} ${PYROOT_EXTRAFLAGS})
+    set(command ${Python3_EXECUTABLE_DEV} ${realfp} ${PYROOT_EXTRAFLAGS})
 
   elseif(DEFINED ARG_MACRO)
     set(command ${root_cmd} ${ARG_MACRO})
@@ -3062,7 +3062,7 @@ macro(ROOTTEST_SETUP_EXECTEST)
 
   if(MSVC)
     if(${realexec} MATCHES "[.]py" AND NOT ${realexec} MATCHES "[.]exe")
-      set(realexec ${Python3_EXECUTABLE} ${realexec})
+      set(realexec ${Python3_EXECUTABLE_DEV} ${realexec})
     else()
       set(realexec ${realexec})
     endif()
diff --git a/cmake/modules/SearchInstalledSoftware.cmake b/cmake/modules/SearchInstalledSoftware.cmake
index ac8fcebe0b11d..751ef4a792315 100644
--- a/cmake/modules/SearchInstalledSoftware.cmake
+++ b/cmake/modules/SearchInstalledSoftware.cmake
@@ -439,6 +439,9 @@ if(Python3_Development_FOUND OR Python3_Development.Module_FOUND)
   endif()
 endif()
 
+# The invocation of the Python 3 executable that should be used for testing:
+set(Python3_EXECUTABLE_DEV ${Python3_EXECUTABLE} -X dev -W error)
+
 #---Check for OpenGL installation-------------------------------------------------------
 # OpenGL is required by various graf3d features that are enabled with opengl=ON,
 # or by the Cocoa-related code that always requires it.
diff --git a/roottest/main/CMakeLists.txt b/roottest/main/CMakeLists.txt
index e2272f4571d92..a4f71c53911f5 100644
--- a/roottest/main/CMakeLists.txt
+++ b/roottest/main/CMakeLists.txt
@@ -11,7 +11,7 @@ configure_file(RootcpReplaceEntireFileCheck.C . COPYONLY)
 # We should explicitly use the Python executable from the Python version that
 # was used to build ROOT. Otherwise, we risk picking up a different Python
 # version at test time.
-set(PY_TOOLS_PREFIX ${Python3_EXECUTABLE} ${ROOT_BINDIR})
+set(PY_TOOLS_PREFIX ${Python3_EXECUTABLE_DEV} ${ROOT_BINDIR})
 set(TOOLS_PREFIX ${ROOT_BINDIR})
 
 if(MSVC)
@@ -519,7 +519,7 @@ if(pyroot)
 set(test_env PYTHONWARNINGS=ignore)
 
 ############################## PATTERN TESTS ############################
-set (TESTPATTERN_EXE ${Python3_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/testPatternToFileNameAndPathSplitList.py)
+set (TESTPATTERN_EXE ${Python3_EXECUTABLE_DEV} ${CMAKE_CURRENT_SOURCE_DIR}/testPatternToFileNameAndPathSplitList.py)
 ROOTTEST_ADD_TEST(SimplePattern1
                   COMMAND ${TESTPATTERN_EXE} test.root
                   OUTREF SimplePattern.ref
diff --git a/roottest/python/JupyROOT/CMakeLists.txt b/roottest/python/JupyROOT/CMakeLists.txt
index 828055119d733..fc23cec51517e 100644
--- a/roottest/python/JupyROOT/CMakeLists.txt
+++ b/roottest/python/JupyROOT/CMakeLists.txt
@@ -23,7 +23,7 @@ foreach(pyfile ${pyfiles})
   get_filename_component(SHORTPYFILE ${pyfile} NAME_WE)
   if (NOT ${SHORTPYFILE} STREQUAL "__init__")
     ROOTTEST_ADD_TEST(${SHORTPYFILE}_doctest
-                      COMMAND ${Python3_EXECUTABLE} ${DOCTEST_LAUNCHER} ${pyfile}
+                      COMMAND ${Python3_EXECUTABLE_DEV} ${DOCTEST_LAUNCHER} ${pyfile}
                       PYTHON_DEPS IPython)
   endif()
 endforeach()
@@ -33,7 +33,7 @@ foreach(NOTEBOOK ${NOTEBOOKS})
   get_filename_component(NOTEBOOKBASE ${NOTEBOOK} NAME_WE)
   ROOTTEST_ADD_TEST(${NOTEBOOKBASE}_notebook
                     COPY_TO_BUILDDIR ${NOTEBOOK}
-                    COMMAND ${Python3_EXECUTABLE} ${NBDIFFUTIL} ${NOTEBOOK}
+                    COMMAND ${Python3_EXECUTABLE_DEV} ${NBDIFFUTIL} ${NOTEBOOK}
                     RUN_SERIAL
                     PYTHON_DEPS jupyter)
 endforeach()
@@ -44,7 +44,7 @@ if(imt)
   get_filename_component(NOTEBOOKBASE ${IMT_NB} NAME_WE)
   ROOTTEST_ADD_TEST(${NOTEBOOKBASE}_notebook
                     COPY_TO_BUILDDIR ${IMT_NB}
-                    COMMAND ${Python3_EXECUTABLE} ${NBDIFFUTIL} ${IMT_NB} "OFF"
+                    COMMAND ${Python3_EXECUTABLE_DEV} ${NBDIFFUTIL} ${IMT_NB} "OFF"
                     RUN_SERIAL
                     PYTHON_DEPS jupyter)
 endif()
diff --git a/roottest/root/meta/CMakeLists.txt b/roottest/root/meta/CMakeLists.txt
index 88625e1c2cf60..2e311c05fa36a 100644
--- a/roottest/root/meta/CMakeLists.txt
+++ b/roottest/root/meta/CMakeLists.txt
@@ -26,7 +26,7 @@ ROOTTEST_ADD_TEST(ROOT5268
                   PASSREGEX "error: unknown type name 'Tbrowser'")
 
 ROOTTEST_ADD_TEST(rlibmap
-                  COMMAND ${Python3_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/rlibmapLauncher.py
+                  COMMAND ${Python3_EXECUTABLE_DEV} ${CMAKE_CURRENT_SOURCE_DIR}/rlibmapLauncher.py
                   PASSRC 1
                   OUTREF  rlibmap.ref)
 
diff --git a/roottest/root/rint/CMakeLists.txt b/roottest/root/rint/CMakeLists.txt
index f346988b0140b..828dab8e368bf 100644
--- a/roottest/root/rint/CMakeLists.txt
+++ b/roottest/root/rint/CMakeLists.txt
@@ -1,7 +1,7 @@
 if(${CMAKE_SYSTEM_PROCESSOR} MATCHES "x86_64.*|x86.*|amd64.*|AMD64.*|i686.*|i386.*")
   # All platforms except of ARM/AARCH64
   ROOTTEST_ADD_TEST(TabCom
-                    COMMAND ${Python3_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/driveTabCom.py
+                    COMMAND ${Python3_EXECUTABLE_DEV} ${CMAKE_CURRENT_SOURCE_DIR}/driveTabCom.py
                     INPUT TabCom_input.txt
                     OUTCNV filterOpt.sh
                     OUTREF TabCom.oref
@@ -9,7 +9,7 @@ if(${CMAKE_SYSTEM_PROCESSOR} MATCHES "x86_64.*|x86.*|amd64.*|AMD64.*|i686.*|i386
                     COPY_TO_BUILDDIR MyClass.h)
 
   ROOTTEST_ADD_TEST(BackslashNewline
-                    COMMAND ${Python3_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/driveTabCom.py
+                    COMMAND ${Python3_EXECUTABLE_DEV} ${CMAKE_CURRENT_SOURCE_DIR}/driveTabCom.py
                     INPUT BackslashNewline_input.txt)
 endif()
 
diff --git a/tutorials/CMakeLists.txt b/tutorials/CMakeLists.txt
index 93f2ab646eb8d..6f7e62b8c366a 100644
--- a/tutorials/CMakeLists.txt
+++ b/tutorials/CMakeLists.txt
@@ -684,7 +684,7 @@ if(geom)
 endif()
 # define Python GNN parsing tutorial needed to run before
 if (ROOT_SONNET_FOUND AND ROOT_GRAPH_NETS_FOUND)
-  ROOT_ADD_TEST(tutorial-machine_learning-TMVA_SOFIE_GNN_Parser COMMAND ${Python3_EXECUTABLE}
+  ROOT_ADD_TEST(tutorial-machine_learning-TMVA_SOFIE_GNN_Parser COMMAND ${Python3_EXECUTABLE_DEV}
   ${CMAKE_CURRENT_SOURCE_DIR}/machine_learning/TMVA_SOFIE_GNN_Parser.py
   PASSRC 0 FAILREGEX "Error in" ": error:" LABELS tutorial ENVIRONMENT ${TUTORIAL_ENV})
   set (machine_learning-TMVA_SOFIE_GNN_Application-depends tutorial-machine_learning-TMVA_SOFIE_GNN_Parser)
@@ -1035,7 +1035,7 @@ if(pyroot)
     endif()
 
     ROOT_ADD_TEST(${tutorial_name}
-                COMMAND ${Python3_EXECUTABLE} ${CMAKE_CURRENT_SOURCE_DIR}/${t}
+                COMMAND ${Python3_EXECUTABLE_DEV} ${CMAKE_CURRENT_SOURCE_DIR}/${t}
                 PASSRC ${rc} FAILREGEX "Error in" ": error:" "segmentation violation"
                 LABELS ${labels}
                 DEPENDS ${tutorial_dependency}