diff --git a/SConstruct b/SConstruct
index e943f8dc043..f32924835d5 100644
--- a/SConstruct
+++ b/SConstruct
@@ -189,7 +189,7 @@ Help(opts.GenerateHelpText(env_base))  # generate help
 
 # add default include paths
 
-env_base.Append(CPPPATH=['#editor', '#'])
+env_base.Prepend(CPPPATH=['#', '#editor'])
 
 # configure ENV for platform
 env_base.platform_exporters = platform_exporters
diff --git a/core/SCsub b/core/SCsub
index d5be74a64fb..06efc8408d2 100644
--- a/core/SCsub
+++ b/core/SCsub
@@ -80,9 +80,9 @@ if env['builtin_zlib']:
 	]
 	thirdparty_zlib_sources = [thirdparty_zlib_dir + file for file in thirdparty_zlib_sources]
 
-	env_thirdparty.Append(CPPPATH=[thirdparty_zlib_dir])
+	env_thirdparty.Prepend(CPPPATH=[thirdparty_zlib_dir])
 	# Needs to be available in main env too
-	env.Append(CPPPATH=[thirdparty_zlib_dir])
+	env.Prepend(CPPPATH=[thirdparty_zlib_dir])
 
 	env_thirdparty.add_source_files(env.core_sources, thirdparty_zlib_sources)
 
@@ -128,9 +128,9 @@ if env['builtin_zstd']:
     ]
     thirdparty_zstd_sources = [thirdparty_zstd_dir + file for file in thirdparty_zstd_sources]
 
-    env_thirdparty.Append(CPPPATH=[thirdparty_zstd_dir, thirdparty_zstd_dir + "common"])
+    env_thirdparty.Prepend(CPPPATH=[thirdparty_zstd_dir, thirdparty_zstd_dir + "common"])
     env_thirdparty.Append(CPPFLAGS="-DZSTD_STATIC_LINKING_ONLY")
-    env.Append(CPPPATH=thirdparty_zstd_dir)
+    env.Prepend(CPPPATH=thirdparty_zstd_dir)
     # Also needed in main env includes will trigger warnings
     env.Append(CPPFLAGS="-DZSTD_STATIC_LINKING_ONLY")
 
diff --git a/drivers/gl_context/SCsub b/drivers/gl_context/SCsub
index efb26a79083..ef5b57a0ccd 100644
--- a/drivers/gl_context/SCsub
+++ b/drivers/gl_context/SCsub
@@ -10,7 +10,7 @@ if (env["platform"] in ["haiku", "osx", "windows", "x11"]):
     ]
     thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-    env.Append(CPPPATH=[thirdparty_dir])
+    env.Prepend(CPPPATH=[thirdparty_dir])
 
     env.Append(CPPFLAGS=['-DGLAD_ENABLED'])
     env.Append(CPPFLAGS=['-DGLES_OVER_GL'])
diff --git a/drivers/png/SCsub b/drivers/png/SCsub
index 97ba1de3db6..9dc80244fff 100644
--- a/drivers/png/SCsub
+++ b/drivers/png/SCsub
@@ -26,9 +26,9 @@ if env['builtin_libpng']:
     ]
     thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-    env_png.Append(CPPPATH=[thirdparty_dir])
+    env_png.Prepend(CPPPATH=[thirdparty_dir])
     # Needed for drivers includes and in platform/javascript
-    env.Append(CPPPATH=[thirdparty_dir])
+    env.Prepend(CPPPATH=[thirdparty_dir])
 
     # Currently .ASM filter_neon.S does not compile on NT.
     import os
diff --git a/modules/assimp/SCsub b/modules/assimp/SCsub
index 61a357809a9..0da7e432e25 100644
--- a/modules/assimp/SCsub
+++ b/modules/assimp/SCsub
@@ -4,19 +4,19 @@ Import('env')
 Import('env_modules')
 
 env_assimp = env_modules.Clone()
-env_assimp.Append(CPPPATH=['#thirdparty/assimp'])
-env_assimp.Append(CPPPATH=['#thirdparty/assimp/include'])
-env_assimp.Append(CPPPATH=['#thirdparty/assimp/code/Importer/IFC'])
-env_assimp.Append(CPPPATH=['#thirdparty/misc'])
-env_assimp.Append(CPPPATH=['#thirdparty/assimp/code'])
-env_assimp.Append(CPPPATH=['#thirdparty/assimp/contrib/irrXML/'])
-env_assimp.Append(CPPPATH=['#thirdparty/assimp/contrib/unzip/'])
-env_assimp.Append(CPPPATH=['#thirdparty/assimp/code/Importer/STEPParser'])
-env_assimp.Append(CPPPATH=['#thirdparty/assimp/'])
-env_assimp.Append(CPPPATH=['#thirdparty/zlib/'])
-env_assimp.Append(CPPPATH=['#thirdparty/assimp/contrib/openddlparser/include'])
-env_assimp.Append(CPPPATH=['#thirdparty/assimp/contrib/rapidjson/include'])
-env_assimp.Append(CPPPATH=['.'])
+env_assimp.Prepend(CPPPATH=['#thirdparty/assimp'])
+env_assimp.Prepend(CPPPATH=['#thirdparty/assimp/include'])
+env_assimp.Prepend(CPPPATH=['#thirdparty/assimp/code/Importer/IFC'])
+env_assimp.Prepend(CPPPATH=['#thirdparty/misc'])
+env_assimp.Prepend(CPPPATH=['#thirdparty/assimp/code'])
+env_assimp.Prepend(CPPPATH=['#thirdparty/assimp/contrib/irrXML/'])
+env_assimp.Prepend(CPPPATH=['#thirdparty/assimp/contrib/unzip/'])
+env_assimp.Prepend(CPPPATH=['#thirdparty/assimp/code/Importer/STEPParser'])
+env_assimp.Prepend(CPPPATH=['#thirdparty/assimp/'])
+env_assimp.Prepend(CPPPATH=['#thirdparty/zlib/'])
+env_assimp.Prepend(CPPPATH=['#thirdparty/assimp/contrib/openddlparser/include'])
+env_assimp.Prepend(CPPPATH=['#thirdparty/assimp/contrib/rapidjson/include'])
+env_assimp.Prepend(CPPPATH=['.'])
 #env_assimp.Append(CPPFLAGS=['-DASSIMP_DOUBLE_PRECISION']) # TODO default to what godot is compiled with for future double support
 env_assimp.Append(CPPFLAGS=['-DASSIMP_BUILD_BOOST_WORKAROUND'])
 env_assimp.Append(CPPFLAGS=['-DOPENDDLPARSER_BUILD'])
diff --git a/modules/bullet/SCsub b/modules/bullet/SCsub
index e7c2fff54c6..16d694c2381 100644
--- a/modules/bullet/SCsub
+++ b/modules/bullet/SCsub
@@ -186,7 +186,7 @@ if env['builtin_bullet']:
 
     thirdparty_sources = [thirdparty_dir + file for file in bullet2_src]
 
-    env_bullet.Append(CPPPATH=[thirdparty_dir])
+    env_bullet.Prepend(CPPPATH=[thirdparty_dir])
     # if env['target'] == "debug" or env['target'] == "release_debug":
     #     env_bullet.Append(CPPFLAGS=['-DBT_DEBUG'])
 
diff --git a/modules/cvtt/SCsub b/modules/cvtt/SCsub
index fcc69d83710..142af0c8003 100644
--- a/modules/cvtt/SCsub
+++ b/modules/cvtt/SCsub
@@ -14,7 +14,7 @@ if env['builtin_squish']:
 
     thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-    env_cvtt.Append(CPPPATH=[thirdparty_dir])
+    env_cvtt.Prepend(CPPPATH=[thirdparty_dir])
 
     env_thirdparty = env_cvtt.Clone()
     env_thirdparty.disable_warnings()
diff --git a/modules/enet/SCsub b/modules/enet/SCsub
index a57a4b29eaa..78d8d43414a 100644
--- a/modules/enet/SCsub
+++ b/modules/enet/SCsub
@@ -21,7 +21,7 @@ if env['builtin_enet']:
     ]
     thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-    env_enet.Append(CPPPATH=[thirdparty_dir])
+    env_enet.Prepend(CPPPATH=[thirdparty_dir])
     env_enet.Append(CPPFLAGS=["-DGODOT_ENET"])
 
     env_thirdparty = env_enet.Clone()
diff --git a/modules/etc/SCsub b/modules/etc/SCsub
index eb2738053be..532b97b0061 100644
--- a/modules/etc/SCsub
+++ b/modules/etc/SCsub
@@ -27,7 +27,7 @@ thirdparty_sources = [
 ]
 thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-env_etc.Append(CPPPATH=[thirdparty_dir])
+env_etc.Prepend(CPPPATH=[thirdparty_dir])
 
 # upstream uses c++11
 if not env.msvc:
diff --git a/modules/freetype/SCsub b/modules/freetype/SCsub
index f2cd9f9a601..0c8b223a9e8 100644
--- a/modules/freetype/SCsub
+++ b/modules/freetype/SCsub
@@ -68,9 +68,9 @@ if env['builtin_freetype']:
         sfnt = env_freetype.Object(sfnt, CPPFLAGS=['-U__OPTIMIZE__'])
     thirdparty_sources += [sfnt]
 
-    env_freetype.Append(CPPPATH=[thirdparty_dir + "/include"])
+    env_freetype.Prepend(CPPPATH=[thirdparty_dir + "/include"])
     # Also needed in main env for scene/
-    env.Append(CPPPATH=[thirdparty_dir + "/include"])
+    env.Prepend(CPPPATH=[thirdparty_dir + "/include"])
 
     env_freetype.Append(CPPFLAGS=['-DFT2_BUILD_LIBRARY', '-DFT_CONFIG_OPTION_USE_PNG'])
     if (env['target'] != 'release'):
@@ -78,7 +78,7 @@ if env['builtin_freetype']:
 
     # Also requires libpng headers
     if env['builtin_libpng']:
-        env_freetype.Append(CPPPATH=["#thirdparty/libpng"])
+        env_freetype.Prepend(CPPPATH=["#thirdparty/libpng"])
 
     env_thirdparty = env_freetype.Clone()
     env_thirdparty.disable_warnings()
diff --git a/modules/gdnative/SCsub b/modules/gdnative/SCsub
index 235f0b97bb4..0cdd5855581 100644
--- a/modules/gdnative/SCsub
+++ b/modules/gdnative/SCsub
@@ -12,7 +12,7 @@ env_gdnative.add_source_files(env.modules_sources, "nativescript/*.cpp")
 env_gdnative.add_source_files(env.modules_sources, "gdnative_library_singleton_editor.cpp")
 env_gdnative.add_source_files(env.modules_sources, "gdnative_library_editor_plugin.cpp")
 
-env_gdnative.Append(CPPPATH=['#modules/gdnative/include/'])
+env_gdnative.Prepend(CPPPATH=['#modules/gdnative/include/'])
 
 Export('env_gdnative')
 
@@ -36,7 +36,7 @@ if ARGUMENTS.get('gdnative_wrapper', False):
     gensource, = env_gdnative.CommandNoCache('gdnative_wrapper_code.gen.cpp', 'gdnative_api.json', run_in_subprocess(gdnative_builders.build_gdnative_wrapper_code))
 
     gd_wrapper_env = env.Clone()
-    gd_wrapper_env.Append(CPPPATH=['#modules/gdnative/include/'])
+    gd_wrapper_env.Prepend(CPPPATH=['#modules/gdnative/include/'])
 
     if gd_wrapper_env['use_lto']:
         if not env.msvc:
diff --git a/modules/gdnative/videodecoder/SCsub b/modules/gdnative/videodecoder/SCsub
index 8d9c1ff50e6..04cc8ed6041 100644
--- a/modules/gdnative/videodecoder/SCsub
+++ b/modules/gdnative/videodecoder/SCsub
@@ -5,5 +5,5 @@ Import('env_modules')
 
 env_vsdecoder_gdnative = env_modules.Clone()
 
-env_vsdecoder_gdnative.Append(CPPPATH=['#modules/gdnative/include/'])
+env_vsdecoder_gdnative.Prepend(CPPPATH=['#modules/gdnative/include/'])
 env_vsdecoder_gdnative.add_source_files(env.modules_sources, '*.cpp')
diff --git a/modules/jpg/SCsub b/modules/jpg/SCsub
index d5f87905eb5..96e8e704dde 100644
--- a/modules/jpg/SCsub
+++ b/modules/jpg/SCsub
@@ -13,7 +13,7 @@ thirdparty_sources = [
 ]
 thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-env_jpg.Append(CPPPATH=[thirdparty_dir])
+env_jpg.Prepend(CPPPATH=[thirdparty_dir])
 
 env_thirdparty = env_jpg.Clone()
 env_thirdparty.disable_warnings()
diff --git a/modules/mono/build_scripts/mono_configure.py b/modules/mono/build_scripts/mono_configure.py
index 160580e1168..4cfa2a5b931 100644
--- a/modules/mono/build_scripts/mono_configure.py
+++ b/modules/mono/build_scripts/mono_configure.py
@@ -70,7 +70,7 @@ def configure(env, env_mono):
         mono_lib_path = os.path.join(mono_root, 'lib')
 
         env.Append(LIBPATH=mono_lib_path)
-        env_mono.Append(CPPPATH=os.path.join(mono_root, 'include', 'mono-2.0'))
+        env_mono.Prepend(CPPPATH=os.path.join(mono_root, 'include', 'mono-2.0'))
 
         if mono_static:
             lib_suffix = Environment()['LIBSUFFIX']
@@ -153,7 +153,7 @@ def configure(env, env_mono):
             mono_lib_path = os.path.join(mono_root, 'lib')
 
             env.Append(LIBPATH=mono_lib_path)
-            env_mono.Append(CPPPATH=os.path.join(mono_root, 'include', 'mono-2.0'))
+            env_mono.Prepend(CPPPATH=os.path.join(mono_root, 'include', 'mono-2.0'))
 
             mono_lib = find_file_in_dir(mono_lib_path, mono_lib_names, prefix='lib', extension='.a')
 
diff --git a/modules/ogg/SCsub b/modules/ogg/SCsub
index 765a9fc11ae..6a72a519fe8 100644
--- a/modules/ogg/SCsub
+++ b/modules/ogg/SCsub
@@ -14,7 +14,7 @@ if env['builtin_libogg']:
     ]
     thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-    env_ogg.Append(CPPPATH=[thirdparty_dir])
+    env_ogg.Prepend(CPPPATH=[thirdparty_dir])
 
     env_thirdparty = env_ogg.Clone()
     env_thirdparty.disable_warnings()
diff --git a/modules/opensimplex/SCsub b/modules/opensimplex/SCsub
index 4235f6a0b9a..311d33b0476 100644
--- a/modules/opensimplex/SCsub
+++ b/modules/opensimplex/SCsub
@@ -12,7 +12,7 @@ thirdparty_sources = [
 ]
 thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-env_opensimplex.Append(CPPPATH=[thirdparty_dir])
+env_opensimplex.Prepend(CPPPATH=[thirdparty_dir])
 
 env_thirdparty = env_opensimplex.Clone()
 env_thirdparty.disable_warnings()
diff --git a/modules/opus/SCsub b/modules/opus/SCsub
index a1325734e23..f3c981dd452 100644
--- a/modules/opus/SCsub
+++ b/modules/opus/SCsub
@@ -206,7 +206,7 @@ if env['builtin_opus']:
 
     # also requires libogg
     if env['builtin_libogg']:
-        env_opus.Append(CPPPATH=["#thirdparty/libogg"])
+        env_opus.Prepend(CPPPATH=["#thirdparty/libogg"])
 
     env_opus.Append(CPPFLAGS=["-DHAVE_CONFIG_H"])
 
@@ -218,7 +218,7 @@ if env['builtin_opus']:
         "silk/fixed",
         "silk/float",
     ]
-    env_opus.Append(CPPPATH=[thirdparty_dir + "/" + dir for dir in thirdparty_include_paths])
+    env_opus.Prepend(CPPPATH=[thirdparty_dir + "/" + dir for dir in thirdparty_include_paths])
 
     if env["platform"] == "android":
         if ("android_arch" in env and env["android_arch"] in ["armv6", "armv7"]):
diff --git a/modules/pvr/SCsub b/modules/pvr/SCsub
index 2e4a792a36a..18da38fbbd1 100644
--- a/modules/pvr/SCsub
+++ b/modules/pvr/SCsub
@@ -17,7 +17,7 @@ thirdparty_sources = [
 ]
 thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-env_pvr.Append(CPPPATH=[thirdparty_dir])
+env_pvr.Prepend(CPPPATH=[thirdparty_dir])
 
 env_thirdparty = env_pvr.Clone()
 env_thirdparty.disable_warnings()
diff --git a/modules/recast/SCsub b/modules/recast/SCsub
index 4a06653968b..94d99681648 100644
--- a/modules/recast/SCsub
+++ b/modules/recast/SCsub
@@ -23,7 +23,7 @@ if env['builtin_recast']:
     ]
     thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-    env_recast.Append(CPPPATH=[thirdparty_dir + "/Include"])
+    env_recast.Prepend(CPPPATH=[thirdparty_dir + "/Include"])
 
     env_thirdparty = env_recast.Clone()
     env_thirdparty.disable_warnings()
diff --git a/modules/regex/SCsub b/modules/regex/SCsub
index 99c25add458..65f354ffa70 100644
--- a/modules/regex/SCsub
+++ b/modules/regex/SCsub
@@ -46,7 +46,7 @@ if env['builtin_pcre2']:
 
     thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-    env_regex.Append(CPPPATH=[thirdparty_dir])
+    env_regex.Prepend(CPPPATH=[thirdparty_dir])
     env_regex.Append(CPPFLAGS=thirdparty_flags)
 
     def pcre2_builtin(width):
diff --git a/modules/squish/SCsub b/modules/squish/SCsub
index 3be85a1efab..15320bcd0cf 100644
--- a/modules/squish/SCsub
+++ b/modules/squish/SCsub
@@ -22,7 +22,7 @@ if env['builtin_squish']:
 
     thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-    env_squish.Append(CPPPATH=[thirdparty_dir])
+    env_squish.Prepend(CPPPATH=[thirdparty_dir])
 
     env_thirdparty = env_squish.Clone()
     env_thirdparty.disable_warnings()
diff --git a/modules/svg/SCsub b/modules/svg/SCsub
index 66d9b3bf753..90bfe22abb7 100644
--- a/modules/svg/SCsub
+++ b/modules/svg/SCsub
@@ -12,10 +12,10 @@ thirdparty_sources = [
 ]
 thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-env_svg.Append(CPPPATH=[thirdparty_dir])
+env_svg.Prepend(CPPPATH=[thirdparty_dir])
 # FIXME: Needed in editor/editor_themes.cpp for now, but ideally there
 # shouldn't be a dependency on modules/ and its own 3rd party deps.
-env.Append(CPPPATH=[thirdparty_dir])
+env.Prepend(CPPPATH=[thirdparty_dir])
 env.Append(CPPFLAGS=["-DSVG_ENABLED"])
 
 env_thirdparty = env_svg.Clone()
diff --git a/modules/theora/SCsub b/modules/theora/SCsub
index f98db2359ca..785eca4c410 100644
--- a/modules/theora/SCsub
+++ b/modules/theora/SCsub
@@ -70,13 +70,13 @@ if env['builtin_libtheora']:
 
     thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-    env_theora.Append(CPPPATH=[thirdparty_dir])
+    env_theora.Prepend(CPPPATH=[thirdparty_dir])
 
     # also requires libogg and libvorbis
     if env['builtin_libogg']:
-        env_theora.Append(CPPPATH=["#thirdparty/libogg"])
+        env_theora.Prepend(CPPPATH=["#thirdparty/libogg"])
     if env['builtin_libvorbis']:
-        env_theora.Append(CPPPATH=["#thirdparty/libvorbis"])
+        env_theora.Prepend(CPPPATH=["#thirdparty/libvorbis"])
 
     env_thirdparty = env_theora.Clone()
     env_thirdparty.disable_warnings()
diff --git a/modules/tinyexr/SCsub b/modules/tinyexr/SCsub
index 3e7bda2bca5..97f9797b58d 100644
--- a/modules/tinyexr/SCsub
+++ b/modules/tinyexr/SCsub
@@ -13,7 +13,7 @@ thirdparty_sources = [
 ]
 thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-env_tinyexr.Append(CPPPATH=[thirdparty_dir])
+env_tinyexr.Prepend(CPPPATH=[thirdparty_dir])
 
 env_thirdparty = env_tinyexr.Clone()
 env_thirdparty.disable_warnings()
diff --git a/modules/upnp/SCsub b/modules/upnp/SCsub
index 2b15f7aee2c..6d669ab73be 100644
--- a/modules/upnp/SCsub
+++ b/modules/upnp/SCsub
@@ -25,7 +25,7 @@ if env['builtin_miniupnpc']:
     ]
     thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-    env_upnp.Append(CPPPATH=[thirdparty_dir])
+    env_upnp.Prepend(CPPPATH=[thirdparty_dir])
     env_upnp.Append(CPPFLAGS=["-DMINIUPNP_STATICLIB"])
 
     env_thirdparty = env_upnp.Clone()
diff --git a/modules/vhacd/SCsub b/modules/vhacd/SCsub
index fdd3ddc1e67..161aed2eb93 100644
--- a/modules/vhacd/SCsub
+++ b/modules/vhacd/SCsub
@@ -24,7 +24,7 @@ thirdparty_sources = [
 
 thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-env_vhacd.Append(CPPPATH=[thirdparty_dir+"/inc"])
+env_vhacd.Prepend(CPPPATH=[thirdparty_dir + "/inc"])
 env_vhacd.Append(CPPFLAGS=["-DGODOT_ENET"])
 
 # upstream uses c++11
diff --git a/modules/vorbis/SCsub b/modules/vorbis/SCsub
index 19587563aba..3824fdd789a 100644
--- a/modules/vorbis/SCsub
+++ b/modules/vorbis/SCsub
@@ -40,11 +40,11 @@ if env['builtin_libvorbis']:
 
     thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-    env_vorbis.Append(CPPPATH=[thirdparty_dir])
+    env_vorbis.Prepend(CPPPATH=[thirdparty_dir])
 
     # also requires libogg
     if env['builtin_libogg']:
-        env_vorbis.Append(CPPPATH=["#thirdparty/libogg"])
+        env_vorbis.Prepend(CPPPATH=["#thirdparty/libogg"])
 
     env_thirdparty = env_vorbis.Clone()
     env_thirdparty.disable_warnings()
diff --git a/modules/webm/SCsub b/modules/webm/SCsub
index dcc9a450445..e57437229f2 100644
--- a/modules/webm/SCsub
+++ b/modules/webm/SCsub
@@ -15,7 +15,7 @@ thirdparty_sources = [
 ]
 thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-env_webm.Append(CPPPATH=[thirdparty_dir, thirdparty_dir + "libwebm/"])
+env_webm.Prepend(CPPPATH=[thirdparty_dir, thirdparty_dir + "libwebm/"])
 
 # upstream uses c++11
 if (not env_webm.msvc):
@@ -23,14 +23,14 @@ if (not env_webm.msvc):
 
 # also requires libogg, libvorbis and libopus
 if env['builtin_libogg']:
-    env_webm.Append(CPPPATH=["#thirdparty/libogg"])
+    env_webm.Prepend(CPPPATH=["#thirdparty/libogg"])
 if env['builtin_libvorbis']:
-    env_webm.Append(CPPPATH=["#thirdparty/libvorbis"])
+    env_webm.Prepend(CPPPATH=["#thirdparty/libvorbis"])
 if env['builtin_opus']:
-    env_webm.Append(CPPPATH=["#thirdparty/opus"])
+    env_webm.Prepend(CPPPATH=["#thirdparty/opus"])
 
 if env['builtin_libvpx']:
-    env_webm.Append(CPPPATH=["#thirdparty/libvpx"])
+    env_webm.Prepend(CPPPATH=["#thirdparty/libvpx"])
     SConscript("libvpx/SCsub")
 
 env_thirdparty = env_webm.Clone()
diff --git a/modules/webm/libvpx/SCsub b/modules/webm/libvpx/SCsub
index 5bf4ea34648..a6be1380a63 100644
--- a/modules/webm/libvpx/SCsub
+++ b/modules/webm/libvpx/SCsub
@@ -256,7 +256,7 @@ libvpx_sources_arm_neon_gas_apple = [libvpx_dir + file for file in libvpx_source
 
 env_libvpx = env_modules.Clone()
 env_libvpx.disable_warnings()
-env_libvpx.Append(CPPPATH=[libvpx_dir])
+env_libvpx.Prepend(CPPPATH=[libvpx_dir])
 
 webm_multithread = env["platform"] != 'javascript'
 
@@ -380,7 +380,7 @@ if webm_cpu_x86:
 elif webm_cpu_arm:
     env_libvpx.add_source_files(env.modules_sources, libvpx_sources_arm)
     if env["platform"] == 'android':
-        env_libvpx.Append(CPPPATH=[libvpx_dir + "third_party/android"])
+        env_libvpx.Prepend(CPPPATH=[libvpx_dir + "third_party/android"])
         env_libvpx.add_source_files(env.modules_sources, [libvpx_dir + "third_party/android/cpu-features.c"])
 
     env_libvpx_neon = env_libvpx.Clone()
diff --git a/modules/webp/SCsub b/modules/webp/SCsub
index fa3896c457d..666628bb44f 100644
--- a/modules/webp/SCsub
+++ b/modules/webp/SCsub
@@ -126,7 +126,7 @@ if env['builtin_libwebp']:
     ]
     thirdparty_sources = [thirdparty_dir + "src/" + file for file in thirdparty_sources]
 
-    env_webp.Append(CPPPATH=[thirdparty_dir, thirdparty_dir + "src/"])
+    env_webp.Prepend(CPPPATH=[thirdparty_dir, thirdparty_dir + "src/"])
 
     env_thirdparty = env_webp.Clone()
     env_thirdparty.disable_warnings()
diff --git a/modules/webrtc/SCsub b/modules/webrtc/SCsub
index 446bd530c2a..868553b8792 100644
--- a/modules/webrtc/SCsub
+++ b/modules/webrtc/SCsub
@@ -10,7 +10,6 @@ use_gdnative = env_webrtc["module_gdnative_enabled"]
 
 if use_gdnative: # GDNative is retained in Javascript for export compatibility
     env_webrtc.Append(CPPDEFINES=['WEBRTC_GDNATIVE_ENABLED'])
-    gdnative_includes = ["#modules/gdnative/include/"]
-    env_webrtc.Append(CPPPATH=gdnative_includes)
+    env_webrtc.Prepend(CPPPATH=["#modules/gdnative/include/"])
 
 env_webrtc.add_source_files(env.modules_sources, "*.cpp")
diff --git a/modules/websocket/SCsub b/modules/websocket/SCsub
index 12b4969cf76..2d2de812200 100644
--- a/modules/websocket/SCsub
+++ b/modules/websocket/SCsub
@@ -75,7 +75,7 @@ if env['builtin_libwebsockets'] and not env["platform"] == "javascript": # alrea
     else: # Unix socket
         thirdparty_sources += Glob(thirdparty_dir + "lib/plat/unix/*.c")
 
-    env_lws.Append(CPPPATH=[thirdparty_dir + 'include/'])
+    env_lws.Prepend(CPPPATH=[thirdparty_dir + 'include/'])
 
     if env['builtin_mbedtls']:
         mbedtls_includes = "#thirdparty/mbedtls/include"
@@ -85,14 +85,14 @@ if env['builtin_libwebsockets'] and not env["platform"] == "javascript": # alrea
     env_lws.Prepend(CPPPATH=wrapper_includes)
 
     if env["platform"] == "windows" or env["platform"] == "uwp":
-        env_lws.Append(CPPPATH=[helper_dir])
+        env_lws.Prepend(CPPPATH=[helper_dir])
 
     if env["platform"] == "uwp":
         env_lws.Append(CPPFLAGS=["/DLWS_MINGW_SUPPORT"])
 
     env_thirdparty = env_lws.Clone()
     env_thirdparty.disable_warnings()
-    env_thirdparty.Append(CPPPATH=[thirdparty_dir + 'lib/'])
+    env_thirdparty.Prepend(CPPPATH=[thirdparty_dir + 'lib/'])
     env_thirdparty.add_source_files(env.modules_sources, thirdparty_sources)
 
 env_lws.add_source_files(env.modules_sources, "*.cpp")
diff --git a/modules/xatlas_unwrap/SCsub b/modules/xatlas_unwrap/SCsub
index 7a40945f271..50e3cb15510 100644
--- a/modules/xatlas_unwrap/SCsub
+++ b/modules/xatlas_unwrap/SCsub
@@ -13,7 +13,7 @@ if env['builtin_xatlas']:
     ]
     thirdparty_sources = [thirdparty_dir + file for file in thirdparty_sources]
 
-    env_xatlas_unwrap.Append(CPPPATH=[thirdparty_dir])
+    env_xatlas_unwrap.Prepend(CPPPATH=[thirdparty_dir])
 
     # upstream uses c++11
     if (not env.msvc):
diff --git a/platform/android/detect.py b/platform/android/detect.py
index 6c67067db72..8d35617d20f 100644
--- a/platform/android/detect.py
+++ b/platform/android/detect.py
@@ -299,7 +299,7 @@ def configure(env):
     env.Append(LIBPATH=[env["ANDROID_NDK_ROOT"] +
                         '/toolchains/' + target_subpath + '/prebuilt/' + host_subpath + '/' + abi_subpath + '/lib'])
 
-    env.Append(CPPPATH=['#platform/android'])
+    env.Prepend(CPPPATH=['#platform/android'])
     env.Append(CPPFLAGS=['-DANDROID_ENABLED', '-DUNIX_ENABLED', '-DNO_FCNTL'])
     env.Append(LIBS=['OpenSLES', 'EGL', 'GLESv3', 'android', 'log', 'z', 'dl'])
 
diff --git a/platform/haiku/detect.py b/platform/haiku/detect.py
index 874b1ab1fb9..f33c77a407d 100644
--- a/platform/haiku/detect.py
+++ b/platform/haiku/detect.py
@@ -137,7 +137,7 @@ def configure(env):
 
     if not env['builtin_miniupnpc']:
         # No pkgconfig file so far, hardcode default paths.
-        env.Append(CPPPATH=["/system/develop/headers/x86/miniupnpc"])
+        env.Prepend(CPPPATH=["/system/develop/headers/x86/miniupnpc"])
         env.Append(LIBS=["miniupnpc"])
 
     # On Linux wchar_t should be 32-bits
@@ -147,7 +147,7 @@ def configure(env):
 
     ## Flags
 
-    env.Append(CPPPATH=['#platform/haiku'])
+    env.Prepend(CPPPATH=['#platform/haiku'])
     env.Append(CPPFLAGS=['-DUNIX_ENABLED', '-DOPENGL_ENABLED', '-DGLES_ENABLED'])
     env.Append(CPPFLAGS=['-DMEDIA_KIT_ENABLED'])
     # env.Append(CPPFLAGS=['-DFREETYPE_ENABLED'])
diff --git a/platform/iphone/detect.py b/platform/iphone/detect.py
index d56e28a4af5..3ed0a4ade71 100644
--- a/platform/iphone/detect.py
+++ b/platform/iphone/detect.py
@@ -165,12 +165,12 @@ def configure(env):
     if env['icloud']:
         env.Append(CPPFLAGS=['-DICLOUD_ENABLED'])
 
-    env.Append(CPPPATH=['$IPHONESDK/usr/include',
-                        '$IPHONESDK/System/Library/Frameworks/OpenGLES.framework/Headers',
-                        '$IPHONESDK/System/Library/Frameworks/AudioUnit.framework/Headers',
-                        ])
+    env.Prepend(CPPPATH=['$IPHONESDK/usr/include',
+                         '$IPHONESDK/System/Library/Frameworks/OpenGLES.framework/Headers',
+                         '$IPHONESDK/System/Library/Frameworks/AudioUnit.framework/Headers',
+                         ])
 
     env['ENV']['CODESIGN_ALLOCATE'] = '/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/codesign_allocate'
 
-    env.Append(CPPPATH=['#platform/iphone'])
+    env.Prepend(CPPPATH=['#platform/iphone'])
     env.Append(CPPFLAGS=['-DIPHONE_ENABLED', '-DUNIX_ENABLED', '-DGLES_ENABLED', '-DCOREAUDIO_ENABLED'])
diff --git a/platform/javascript/detect.py b/platform/javascript/detect.py
index c7acbde3f7d..145ce8d83d4 100644
--- a/platform/javascript/detect.py
+++ b/platform/javascript/detect.py
@@ -103,7 +103,7 @@ def configure(env):
 
     ## Compile flags
 
-    env.Append(CPPPATH=['#platform/javascript'])
+    env.Prepend(CPPPATH=['#platform/javascript'])
     env.Append(CPPDEFINES=['JAVASCRIPT_ENABLED', 'UNIX_ENABLED'])
 
     # No multi-threading (SharedArrayBuffer) available yet,
diff --git a/platform/osx/detect.py b/platform/osx/detect.py
index 80248971955..4c88f91d131 100644
--- a/platform/osx/detect.py
+++ b/platform/osx/detect.py
@@ -126,7 +126,7 @@ def configure(env):
 
     ## Flags
 
-    env.Append(CPPPATH=['#platform/osx'])
+    env.Prepend(CPPPATH=['#platform/osx'])
     env.Append(CPPFLAGS=['-DOSX_ENABLED', '-DUNIX_ENABLED', '-DGLES_ENABLED', '-DAPPLE_STYLE_KEYS', '-DCOREAUDIO_ENABLED', '-DCOREMIDI_ENABLED'])
     env.Append(LINKFLAGS=['-framework', 'Cocoa', '-framework', 'Carbon', '-framework', 'OpenGL', '-framework', 'AGL', '-framework', 'AudioUnit', '-framework', 'CoreAudio', '-framework', 'CoreMIDI', '-lz', '-framework', 'IOKit', '-framework', 'ForceFeedback', '-framework', 'CoreVideo'])
     env.Append(LIBS=['pthread'])
diff --git a/platform/server/detect.py b/platform/server/detect.py
index 5306a2bf692..08c2eb6aaf5 100644
--- a/platform/server/detect.py
+++ b/platform/server/detect.py
@@ -201,7 +201,7 @@ def configure(env):
 
     if not env['builtin_miniupnpc']:
         # No pkgconfig file so far, hardcode default paths.
-        env.Append(CPPPATH=["/usr/include/miniupnpc"])
+        env.Prepend(CPPPATH=["/usr/include/miniupnpc"])
         env.Append(LIBS=["miniupnpc"])
 
     # On Linux wchar_t should be 32-bits
@@ -215,7 +215,7 @@ def configure(env):
     if not env['builtin_zlib']:
         env.ParseConfig('pkg-config zlib --cflags --libs')
 
-    env.Append(CPPPATH=['#platform/server'])
+    env.Prepend(CPPPATH=['#platform/server'])
     env.Append(CPPFLAGS=['-DSERVER_ENABLED', '-DUNIX_ENABLED'])
 
     if (platform.system() == "Darwin"):
diff --git a/platform/uwp/detect.py b/platform/uwp/detect.py
index 17f82424661..00f419f4f09 100644
--- a/platform/uwp/detect.py
+++ b/platform/uwp/detect.py
@@ -77,7 +77,7 @@ def configure(env):
 
     # ANGLE
     angle_root = os.getenv("ANGLE_SRC_PATH")
-    env.Append(CPPPATH=[angle_root + '/include'])
+    env.Prepend(CPPPATH=[angle_root + '/include'])
     jobs = str(env.GetOption("num_jobs"))
     angle_build_cmd = "msbuild.exe " + angle_root + "/winrt/10/src/angle.sln /nologo /v:m /m:" + jobs + " /p:Configuration=Release /p:Platform="
 
@@ -137,7 +137,7 @@ def configure(env):
 
     ## Compile flags
 
-    env.Append(CPPPATH=['#platform/uwp', '#drivers/windows'])
+    env.Prepend(CPPPATH=['#platform/uwp', '#drivers/windows'])
     env.Append(CPPFLAGS=['/DUWP_ENABLED', '/DWINDOWS_ENABLED', '/DTYPED_METHOD_BIND'])
     env.Append(CPPFLAGS=['/DGLES_ENABLED', '/DGL_GLEXT_PROTOTYPES', '/DEGL_EGLEXT_PROTOTYPES', '/DANGLE_ENABLED'])
     winver = "0x0602" # Windows 8 is the minimum target for UWP build
diff --git a/platform/windows/detect.py b/platform/windows/detect.py
index 5c38eebf04b..4b4b5074991 100644
--- a/platform/windows/detect.py
+++ b/platform/windows/detect.py
@@ -201,7 +201,7 @@ def configure_msvc(env, manual_msvc_config):
     env.AppendUnique(CXXFLAGS=['/TP']) # assume all sources are C++
     if manual_msvc_config: # should be automatic if SCons found it
         if os.getenv("WindowsSdkDir") is not None:
-            env.Append(CPPPATH=[os.getenv("WindowsSdkDir") + "/Include"])
+            env.Prepend(CPPPATH=[os.getenv("WindowsSdkDir") + "/Include"])
         else:
             print("Missing environment variable: WindowsSdkDir")
 
@@ -239,7 +239,7 @@ def configure_msvc(env, manual_msvc_config):
             env.AppendUnique(LINKFLAGS=['/LTCG'])
 
     if manual_msvc_config:
-        env.Append(CPPPATH=[p for p in os.getenv("INCLUDE").split(";")])
+        env.Prepend(CPPPATH=[p for p in os.getenv("INCLUDE").split(";")])
         env.Append(LIBPATH=[p for p in os.getenv("LIB").split(";")])
 
     # Incremental linking fix
@@ -342,7 +342,7 @@ def configure_mingw(env):
 
 def configure(env):
     # At this point the env has been set up with basic tools/compilers.
-    env.Append(CPPPATH=['#platform/windows'])
+    env.Prepend(CPPPATH=['#platform/windows'])
 
     print("Configuring for Windows: target=%s, bits=%s" % (env['target'], env['bits']))
 
diff --git a/platform/x11/detect.py b/platform/x11/detect.py
index f8ae5e9acb3..933ee6b72e9 100644
--- a/platform/x11/detect.py
+++ b/platform/x11/detect.py
@@ -275,7 +275,7 @@ def configure(env):
 
     if not env['builtin_miniupnpc']:
         # No pkgconfig file so far, hardcode default paths.
-        env.Append(CPPPATH=["/usr/include/miniupnpc"])
+        env.Prepend(CPPPATH=["/usr/include/miniupnpc"])
         env.Append(LIBS=["miniupnpc"])
 
     # On Linux wchar_t should be 32-bits
@@ -316,7 +316,7 @@ def configure(env):
     if not env['builtin_zlib']:
         env.ParseConfig('pkg-config zlib --cflags --libs')
 
-    env.Append(CPPPATH=['#platform/x11'])
+    env.Prepend(CPPPATH=['#platform/x11'])
     env.Append(CPPFLAGS=['-DX11_ENABLED', '-DUNIX_ENABLED', '-DOPENGL_ENABLED', '-DGLES_ENABLED'])
     env.Append(LIBS=['GL', 'pthread'])