diff --git a/recipes/cern-root/all/conandata.yml b/recipes/cern-root/all/conandata.yml
index 95fdfa6c18619..5cd0942b4f4fb 100644
--- a/recipes/cern-root/all/conandata.yml
+++ b/recipes/cern-root/all/conandata.yml
@@ -6,3 +6,7 @@ patches:
   "v6-22-06":
     - patch_file: "patches/0001-add-missing-includes.patch"
     - patch_file: "patches/0002-cmake-missing-link-libraries.patch"
+    - patch_file: "patches/0003-backport-empty-define-filtering.patch"
+      patch_description: "Backport filtering of empty -D flags"
+      patch_type: "portability"
+      patch_source: "https://github.com/root-project/root/blob/798b9b079f7b6c136bdaaf6787729a1bef865429/cmake/modules/RootMacros.cmake"
diff --git a/recipes/cern-root/all/conanfile.py b/recipes/cern-root/all/conanfile.py
index a6e288368cf09..eccbe35013d65 100644
--- a/recipes/cern-root/all/conanfile.py
+++ b/recipes/cern-root/all/conanfile.py
@@ -4,7 +4,7 @@
 
 from conan import ConanFile
 from conan.errors import ConanInvalidConfiguration
-from conan.tools.build import check_min_cppstd
+from conan.tools.build import check_min_cppstd, valid_min_cppstd
 from conan.tools.cmake import CMake, CMakeDeps, CMakeToolchain, cmake_layout
 from conan.tools.files import apply_conandata_patches, copy, export_conandata_patches, get, replace_in_file, rm, rmdir
 from conan.tools.scm import Version
@@ -137,10 +137,12 @@ def _make_file_executable(filename):
 
     def generate(self):
         tc = CMakeToolchain(self)
+        tc.variables["CMAKE_PROJECT_ROOT_INCLUDE"] = "conan_deps.cmake"
+        if not valid_min_cppstd(self, self._minimum_cpp_standard):
+            tc.variables["CMAKE_CXX_STANDARD"] = self._minimum_cpp_standard
+        tc.variables["BUILD_SHARED_LIBS"] = True
         # Configure build options found at
         # https://github.com/root-project/root/blob/v6-22-06/cmake/modules/RootBuildOptions.cmake#L80-L193
-        tc.variables["CMAKE_CXX_STANDARD"] = self._cmake_cxx_standard
-        tc.variables["BUILD_SHARED_LIBS"] = True
         tc.variables["shared"] = True
         tc.variables["asimage"] = self.options.asimage
         tc.variables["fail-on-missing"] = True
@@ -281,16 +283,10 @@ def _patch_sources(self):
         apply_conandata_patches(self)
         self._patch_source_cmake()
         self._fix_source_permissions()
-        replace_in_file(self, os.path.join(self.source_folder, "CMakeLists.txt"),
-                        "project(ROOT)", "project(ROOT)\n\ninclude(conan_deps.cmake)")
         # Relax TBB version check
         replace_in_file(self, os.path.join(self.source_folder, "cmake", "modules", "SearchInstalledSoftware.cmake"),
                         "TBB 2018", "TBB")
 
-    @property
-    def _cmake_cxx_standard(self):
-        return str(self.settings.get_safe("compiler.cppstd", self._minimum_cpp_standard))
-
     @property
     def _cmake_pyrootopt(self):
         return self.options.python != "off"
diff --git a/recipes/cern-root/all/patches/0003-backport-empty-define-filtering.patch b/recipes/cern-root/all/patches/0003-backport-empty-define-filtering.patch
new file mode 100644
index 0000000000000..37b86fd1997f9
--- /dev/null
+++ b/recipes/cern-root/all/patches/0003-backport-empty-define-filtering.patch
@@ -0,0 +1,57 @@
+--- cmake/modules/RootMacros.cmake
++++ cmake/modules/RootMacros.cmake
+@@ -179,7 +179,10 @@
+ 
+   IF(TARGET ${dictionary})
+     LIST(APPEND include_dirs $<TARGET_PROPERTY:${dictionary},INCLUDE_DIRECTORIES>)
+-    LIST(APPEND definitions $<TARGET_PROPERTY:${dictionary},COMPILE_DEFINITIONS>)
++    # The COMPILE_DEFINITIONS list might contain empty elements. These are
++    # removed with the FILTER generator expression, excluding elements that
++    # match the ^$ regexp (only matches empty strings).
++    LIST(APPEND definitions "$<FILTER:$<TARGET_PROPERTY:${dictionary},COMPILE_DEFINITIONS>,EXCLUDE,^$>")
+   ENDIF()
+ 
+   add_custom_command(
+@@ -187,7 +190,7 @@
+     COMMAND ${ROOT_genreflex_CMD}
+     ARGS ${headerfiles} -o ${gensrcdict} ${rootmapopts} --select=${selectionfile}
+          --gccxmlpath=${GCCXML_home}/bin ${ARG_OPTIONS}
+-         "-I$<JOIN:${include_dirs},;-I>"
++         "-I$<JOIN:$<REMOVE_DUPLICATES:$<FILTER:${include_dirs},EXCLUDE,^$>>,;-I>"
+          "$<$<BOOL:$<JOIN:${definitions},>>:-D$<JOIN:${definitions},;-D>>"
+     DEPENDS ${headerfiles} ${selectionfile} ${ARG_DEPENDS}
+ 
+@@ -633,21 +636,26 @@
+ 
+     # get target properties added after call to ROOT_GENERATE_DICTIONARY()
+     if(TARGET ${ARG_MODULE})
+-      if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.15)
+-        set(module_incs $<REMOVE_DUPLICATES:$<TARGET_PROPERTY:${ARG_MODULE},INCLUDE_DIRECTORIES>>)
+-      else()
+-        set(module_incs $<TARGET_PROPERTY:${ARG_MODULE},INCLUDE_DIRECTORIES>)
+-      endif()
+-      set(module_defs $<TARGET_PROPERTY:${ARG_MODULE},COMPILE_DEFINITIONS>)
++      # NOTE that module_sysincs is already part of ${module_sysincs}. But -isystem "wins",
++      # and list exclusion for generator expressions is too complex.
++      set(module_incs $<REMOVE_DUPLICATES:$<TARGET_PROPERTY:${ARG_MODULE},INCLUDE_DIRECTORIES>>)
++      set(module_sysincs $<REMOVE_DUPLICATES:$<TARGET_PROPERTY:${ARG_MODULE},INTERFACE_SYSTEM_INCLUDE_DIRECTORIES>>)
++      # The COMPILE_DEFINITIONS list might contain empty elements. These are
++      # removed with the FILTER generator expression, excluding elements that
++      # match the ^$ regexp (only matches empty strings).
++      set(module_defs "$<FILTER:$<TARGET_PROPERTY:${ARG_MODULE},COMPILE_DEFINITIONS>,EXCLUDE,^$>")
+     endif()
+   endif()
+ 
+   #---call rootcint------------------------------------------
+   add_custom_command(OUTPUT ${dictionary}.cxx ${pcm_name} ${rootmap_name} ${cpp_module_file}
+                      COMMAND ${command} -v2 -f  ${dictionary}.cxx ${newargs} ${excludepathsargs} ${rootmapargs}
++                                        ${ARG_OPTIONS}
+                                         ${definitions} "$<$<BOOL:${module_defs}>:-D$<JOIN:${module_defs},;-D>>"
++                                        ${compIncPaths}
++                                        "$<$<BOOL:${module_sysincs}>:-isystem;$<JOIN:${module_sysincs},;-isystem;>>"
+                                         ${includedirs} "$<$<BOOL:${module_incs}>:-I$<JOIN:${module_incs},;-I>>"
+-                                        ${ARG_OPTIONS} ${headerfiles} ${_linkdef}
++                                        ${headerfiles} ${_linkdef}
+                      IMPLICIT_DEPENDS ${_implicitdeps}
+                      DEPENDS ${_list_of_header_dependencies} ${_linkdef} ${ROOTCINTDEP}
+                              ${MODULE_LIB_DEPENDENCY} ${ARG_EXTRA_DEPENDENCIES}