diff --git a/.github/workflows/root-ci.yml b/.github/workflows/root-ci.yml
index af708beb91aa8..b5d57741c12ca 100644
--- a/.github/workflows/root-ci.yml
+++ b/.github/workflows/root-ci.yml
@@ -601,7 +601,7 @@ jobs:
 
       - name: CTest in post-install test project
         working-directory: ${{ env.POST_INSTALL_DIR }}
-        run: ctest -j $(nproc)
+        run: ctest --output-on-failure -j $(nproc)
 
   event_file:
     # For any event that is not a PR, the CI will always run. In PRs, the CI
diff --git a/bindings/pyroot/cppyy/CPyCppyy/CMakeLists.txt b/bindings/pyroot/cppyy/CPyCppyy/CMakeLists.txt
index 98a93a5c24c0f..28e6e993fd723 100644
--- a/bindings/pyroot/cppyy/CPyCppyy/CMakeLists.txt
+++ b/bindings/pyroot/cppyy/CPyCppyy/CMakeLists.txt
@@ -73,7 +73,8 @@ endif()
 add_library(cppyy SHARED src/CPyCppyyPyModule.cxx)
 
 # Set the suffix to '.so' and the prefix to 'lib'
-set_target_properties(cppyy PROPERTIES  ${ROOT_LIBRARY_PROPERTIES})
+set_target_properties(cppyy PROPERTIES  ${ROOT_LIBRARY_PROPERTIES}
+  LIBRARY_OUTPUT_DIRECTORY ${localruntimedir}/cppyy)
 if(MSVC)
   target_link_libraries(cppyy PRIVATE CPyCppyy)
   set_target_properties(cppyy PROPERTIES WINDOWS_EXPORT_ALL_SYMBOLS TRUE)
@@ -116,7 +117,7 @@ set_property(GLOBAL APPEND PROPERTY ROOT_EXPORTED_TARGETS cppyy)
 
 if(NOT MSVC)
   # Make sure that relative RUNPATH to main ROOT libraries is always correct.
-  ROOT_APPEND_LIBDIR_TO_INSTALL_RPATH(cppyy ${CMAKE_INSTALL_PYTHONDIR})
+  ROOT_APPEND_LIBDIR_TO_INSTALL_RPATH(cppyy ${CMAKE_INSTALL_PYTHONDIR}/cppyy)
   ROOT_APPEND_LIBDIR_TO_INSTALL_RPATH(CPyCppyy ${CMAKE_INSTALL_LIBDIR})
 endif()
 
@@ -127,9 +128,9 @@ install(TARGETS CPyCppyy EXPORT ${CMAKE_PROJECT_NAME}Exports
                             ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR} COMPONENT libraries)
 
 install(TARGETS cppyy EXPORT ${CMAKE_PROJECT_NAME}Exports
-                            RUNTIME DESTINATION ${CMAKE_INSTALL_PYTHONDIR} COMPONENT libraries
-                            LIBRARY DESTINATION ${CMAKE_INSTALL_PYTHONDIR} COMPONENT libraries
-                            ARCHIVE DESTINATION ${CMAKE_INSTALL_PYTHONDIR} COMPONENT libraries)
+                            RUNTIME DESTINATION ${CMAKE_INSTALL_PYTHONDIR}/cppyy COMPONENT libraries
+                            LIBRARY DESTINATION ${CMAKE_INSTALL_PYTHONDIR}/cppyy COMPONENT libraries
+                            ARCHIVE DESTINATION ${CMAKE_INSTALL_PYTHONDIR}/cppyy COMPONENT libraries)
 
 file(COPY ${headers} DESTINATION ${CMAKE_BINARY_DIR}/include/CPyCppyy)
 
diff --git a/bindings/pyroot/cppyy/cppyy/python/cppyy/__init__.py b/bindings/pyroot/cppyy/cppyy/python/cppyy/__init__.py
index b04aeffca000e..bab7a61f66372 100644
--- a/bindings/pyroot/cppyy/cppyy/python/cppyy/__init__.py
+++ b/bindings/pyroot/cppyy/cppyy/python/cppyy/__init__.py
@@ -66,6 +66,12 @@
 from . import _typemap
 from ._version import __version__
 
+# Help Windows locate cppyy/libcppyy, which should be in the same location as the current file:
+if "win32" in sys.platform:
+    cppyy_path = os.path.dirname(__file__)
+    os.add_dll_directory(cppyy_path)
+    os.add_dll_directory(os.path.dirname(cppyy_path))
+
 # import separately instead of in the above try/except block for easier to
 # understand tracebacks
 if ispypy:
@@ -339,7 +345,9 @@ def add_library_path(path):
 
         apipath_extra = os.path.join(os.path.dirname(apipath), 'site', 'python'+ldversion)
         if not os.path.exists(os.path.join(apipath_extra, 'CPyCppyy')):
-            import glob, libcppyy
+            import glob
+
+            import cppyy.libcppyy as libcppyy
             ape = os.path.dirname(libcppyy.__file__)
           # a "normal" structure finds the include directory up to 3 levels up,
           # ie. dropping lib/pythonx.y[md]/site-packages
diff --git a/bindings/pyroot/cppyy/cppyy/python/cppyy/_cpython_cppyy.py b/bindings/pyroot/cppyy/cppyy/python/cppyy/_cpython_cppyy.py
index f002931b0e717..42cfc379569a4 100644
--- a/bindings/pyroot/cppyy/cppyy/python/cppyy/_cpython_cppyy.py
+++ b/bindings/pyroot/cppyy/cppyy/python/cppyy/_cpython_cppyy.py
@@ -27,7 +27,7 @@
 except ImportError:
     c = None
 
-import libcppyy as _backend
+import cppyy.libcppyy as _backend
 
 if c is not None:
     _backend._cpp_backend = c
diff --git a/roottest/python/basic/PyROOT_datatypetest.py b/roottest/python/basic/PyROOT_datatypetest.py
index fc6da85cb4b25..9e24ec0f54c58 100644
--- a/roottest/python/basic/PyROOT_datatypetest.py
+++ b/roottest/python/basic/PyROOT_datatypetest.py
@@ -37,9 +37,7 @@ def setup_class(cls):
         cls.datatypes = cppyy.load_reflection_info(cls.test_dct)
         cls.N = cppyy.gbl.N
         # In new Cppyy, nullptr can't be found in gbl.
-        # Take it from libcppyy (we could also use ROOT.nullptr)
-        import libcppyy
-        cls.nullptr = libcppyy.nullptr
+        cls.nullptr = cppyy._backend.nullptr
 
     def test01_load_reflection_cache(self):
         """Loading reflection info twice should result in the same object"""
@@ -580,7 +578,7 @@ def test09_global_builtin_types(self):
         raises(ValueError, setattr, gbl, 'g_uint',    -1)
         raises(ValueError, setattr, gbl, 'g_ulong',   -1)
         raises(ValueError, setattr, gbl, 'g_ulong64', -1)
-                        
+
     def test10_global_ptr(self):
         """Access of global objects through a pointer"""
 
diff --git a/roottest/python/basic/PyROOT_datatypetest_numpy.py b/roottest/python/basic/PyROOT_datatypetest_numpy.py
index 097dceeef7178..857814c7c8f13 100644
--- a/roottest/python/basic/PyROOT_datatypetest_numpy.py
+++ b/roottest/python/basic/PyROOT_datatypetest_numpy.py
@@ -37,9 +37,7 @@ def setup_class(cls):
         cls.datatypes = cppyy.load_reflection_info(cls.test_dct)
         cls.N = cppyy.gbl.N
         # In new Cppyy, nullptr can't be found in gbl.
-        # Take it from libcppyy (we could also use ROOT.nullptr)
-        import libcppyy
-        cls.nullptr = libcppyy.nullptr
+        cls.nullptr = cppyy._backend.nullptr
 
     def test01_buffer_to_numpy(self):
         """Wrap buffer with NumPy array"""