diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6b350f6e3..23725381d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -44,8 +44,8 @@ option(ASSIMP_HUNTER_ENABLED "Enable Hunter package manager support" OFF)
 IF(ASSIMP_HUNTER_ENABLED)
   include("cmake/HunterGate.cmake")
   HunterGate(
-    URL "https://github.com/ruslo/hunter/archive/v0.23.176.tar.gz"
-    SHA1 "2e9ae973d028660b735ac4c6142725ca36a0048a"
+    URL "https://github.com/cpp-pm/hunter/archive/v0.23.261.tar.gz"
+    SHA1 "1540dad7b97c849784a09e8c452ba811c9f71ba2"
   )
 
   add_definitions(-DASSIMP_USE_HUNTER)
@@ -357,6 +357,34 @@ IF (NOT TARGET uninstall)
   ADD_CUSTOM_TARGET(uninstall "${CMAKE_COMMAND}" -P "${CMAKE_CURRENT_BINARY_DIR}/cmake_uninstall.cmake")
 ENDIF()
 
+# cmake configuration files
+if(${BUILD_SHARED_LIBS})
+  set(BUILD_LIB_TYPE SHARED)
+else()
+  set(BUILD_LIB_TYPE STATIC)
+endif()
+
+IF( UNIX )
+  # Use GNUInstallDirs for Unix predefined directories
+  INCLUDE(GNUInstallDirs)
+
+  SET( ASSIMP_LIB_INSTALL_DIR ${CMAKE_INSTALL_LIBDIR})
+  SET( ASSIMP_INCLUDE_INSTALL_DIR ${CMAKE_INSTALL_INCLUDEDIR})
+  SET( ASSIMP_BIN_INSTALL_DIR ${CMAKE_INSTALL_BINDIR})
+ELSE()
+  # Cache these to allow the user to override them on non-Unix platforms
+  SET( ASSIMP_LIB_INSTALL_DIR "lib" CACHE STRING
+    "Path the built library files are installed to." )
+  SET( ASSIMP_INCLUDE_INSTALL_DIR "include" CACHE STRING
+    "Path the header files are installed to." )
+  SET( ASSIMP_BIN_INSTALL_DIR "bin" CACHE STRING
+    "Path the tool executables are installed to." )
+
+  SET(CMAKE_INSTALL_FULL_INCLUDEDIR ${CMAKE_INSTALL_PREFIX}/${ASSIMP_INCLUDE_INSTALL_DIR})
+  SET(CMAKE_INSTALL_FULL_LIBDIR ${CMAKE_INSTALL_PREFIX}/${ASSIMP_LIB_INSTALL_DIR})
+  SET(CMAKE_INSTALL_FULL_BINDIR ${CMAKE_INSTALL_PREFIX}/${ASSIMP_BIN_INSTALL_DIR})
+ENDIF()
+
 IF(ASSIMP_HUNTER_ENABLED)
   set(CONFIG_INSTALL_DIR "lib/cmake/${PROJECT_NAME}")
   set(INCLUDE_INSTALL_DIR "include")
@@ -395,34 +423,6 @@ IF(ASSIMP_HUNTER_ENABLED)
       DESTINATION "${CONFIG_INSTALL_DIR}"
   )
 ELSE()
-  # cmake configuration files
-  if(${BUILD_SHARED_LIBS})
-    set(BUILD_LIB_TYPE SHARED)
-  else()
-    set(BUILD_LIB_TYPE STATIC)
-  endif()
-
-  IF( UNIX )
-    # Use GNUInstallDirs for Unix predefined directories
-    INCLUDE(GNUInstallDirs)
-
-    SET( ASSIMP_LIB_INSTALL_DIR ${CMAKE_INSTALL_LIBDIR})
-    SET( ASSIMP_INCLUDE_INSTALL_DIR ${CMAKE_INSTALL_INCLUDEDIR})
-    SET( ASSIMP_BIN_INSTALL_DIR ${CMAKE_INSTALL_BINDIR})
-  ELSE()
-    # Cache these to allow the user to override them on non-Unix platforms
-    SET( ASSIMP_LIB_INSTALL_DIR "lib" CACHE STRING
-      "Path the built library files are installed to." )
-    SET( ASSIMP_INCLUDE_INSTALL_DIR "include" CACHE STRING
-      "Path the header files are installed to." )
-    SET( ASSIMP_BIN_INSTALL_DIR "bin" CACHE STRING
-      "Path the tool executables are installed to." )
-
-    SET(CMAKE_INSTALL_FULL_INCLUDEDIR ${CMAKE_INSTALL_PREFIX}/${ASSIMP_INCLUDE_INSTALL_DIR})
-    SET(CMAKE_INSTALL_FULL_LIBDIR ${CMAKE_INSTALL_PREFIX}/${ASSIMP_LIB_INSTALL_DIR})
-    SET(CMAKE_INSTALL_FULL_BINDIR ${CMAKE_INSTALL_PREFIX}/${ASSIMP_BIN_INSTALL_DIR})
-  ENDIF()
-
   CONFIGURE_FILE("${CMAKE_CURRENT_SOURCE_DIR}/assimp-config.cmake.in"         "${CMAKE_CURRENT_BINARY_DIR}/assimp-config.cmake" @ONLY IMMEDIATE)
   CONFIGURE_FILE("${CMAKE_CURRENT_SOURCE_DIR}/assimpTargets.cmake.in"         "${CMAKE_CURRENT_BINARY_DIR}/assimpTargets.cmake" @ONLY IMMEDIATE)
   IF (is_multi_config)
diff --git a/cmake/assimp-hunter-config.cmake.in b/cmake/assimp-hunter-config.cmake.in
index 34762ac54..8707602e5 100644
--- a/cmake/assimp-hunter-config.cmake.in
+++ b/cmake/assimp-hunter-config.cmake.in
@@ -2,7 +2,7 @@
 
 find_package(RapidJSON CONFIG REQUIRED)
 find_package(ZLIB CONFIG REQUIRED)
-find_package(utf8 CONFIG REQUIRED)
+find_package(utf8cpp CONFIG REQUIRED)
 find_package(irrXML CONFIG REQUIRED)
 find_package(minizip CONFIG REQUIRED)
 find_package(openddlparser CONFIG REQUIRED)
diff --git a/code/AssetLib/MMD/MMDPmxParser.cpp b/code/AssetLib/MMD/MMDPmxParser.cpp
index 6421f38cb..7ac5ac399 100644
--- a/code/AssetLib/MMD/MMDPmxParser.cpp
+++ b/code/AssetLib/MMD/MMDPmxParser.cpp
@@ -43,7 +43,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "MMDPmxParser.h"
 #include <assimp/StringUtils.h>
 #ifdef ASSIMP_USE_HUNTER
-#  include <utf8/utf8.h>
+#  include <utf8.h>
 #else
 #  include "../contrib/utf8cpp/source/utf8.h"
 #endif
diff --git a/code/AssetLib/SIB/SIBImporter.cpp b/code/AssetLib/SIB/SIBImporter.cpp
index b36c6d9b1..33beb0087 100644
--- a/code/AssetLib/SIB/SIBImporter.cpp
+++ b/code/AssetLib/SIB/SIBImporter.cpp
@@ -59,7 +59,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <assimp/StreamReader.h>
 #include <assimp/TinyFormatter.h>
 #ifdef ASSIMP_USE_HUNTER
-#include <utf8/utf8.h>
+#include <utf8.h>
 #else
 //#  include "../contrib/ConvertUTF/ConvertUTF.h"
 #include "../contrib/utf8cpp/source/utf8.h"
diff --git a/code/AssetLib/STEPParser/STEPFileEncoding.cpp b/code/AssetLib/STEPParser/STEPFileEncoding.cpp
index d917c28f3..1d1150c08 100644
--- a/code/AssetLib/STEPParser/STEPFileEncoding.cpp
+++ b/code/AssetLib/STEPParser/STEPFileEncoding.cpp
@@ -46,7 +46,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "STEPFileEncoding.h"
 #include <assimp/fast_atof.h>
 #ifdef ASSIMP_USE_HUNTER
-#  include <utf8/utf8.h>
+#  include <utf8.h>
 #else
 #  include <contrib/utf8cpp/source/utf8.h>
 #endif
diff --git a/code/AssetLib/X3D/FIReader.cpp b/code/AssetLib/X3D/FIReader.cpp
index de9f035f2..c1b439bda 100644
--- a/code/AssetLib/X3D/FIReader.cpp
+++ b/code/AssetLib/X3D/FIReader.cpp
@@ -61,7 +61,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include <assimp/MemoryIOWrapper.h>
 #include <assimp/irrXMLWrapper.h>
 #ifdef ASSIMP_USE_HUNTER
-#  include <utf8/utf8.h>
+#  include <utf8.h>
 #else
 #  include "../contrib/utf8cpp/source/utf8.h"
 #endif
diff --git a/code/AssetLib/glTF/glTFAsset.inl b/code/AssetLib/glTF/glTFAsset.inl
index 116f76535..c72b9698d 100644
--- a/code/AssetLib/glTF/glTFAsset.inl
+++ b/code/AssetLib/glTF/glTFAsset.inl
@@ -836,8 +836,8 @@ inline void Mesh::Read(Value &pJSON_Object, Asset &pAsset_Root) {
 
     if (json_extensions == nullptr) goto mr_skip_extensions;
 
-    for (Value::MemberIterator it_memb = json_extensions->MemberBegin(); it_memb != json_extensions->MemberEnd(); it_memb++) {
 #ifdef ASSIMP_IMPORTER_GLTF_USE_OPEN3DGC
+    for (Value::MemberIterator it_memb = json_extensions->MemberBegin(); it_memb != json_extensions->MemberEnd(); it_memb++) {
         if (it_memb->name.GetString() == std::string("Open3DGC-compression")) {
             // Search for compressed data.
             // Compressed data contain description of part of "buffer" which is encoded. This part must be decoded and
@@ -887,11 +887,11 @@ inline void Mesh::Read(Value &pJSON_Object, Asset &pAsset_Root) {
             Extension.push_back(ext_o3dgc); // store info in mesh extensions list.
         } // if(it_memb->name.GetString() == "Open3DGC-compression")
         else
-#endif
         {
             throw DeadlyImportError(std::string("GLTF: Unknown mesh extension: \"") + it_memb->name.GetString() + "\".");
         }
     } // for(Value::MemberIterator it_memb = json_extensions->MemberBegin(); it_memb != json_extensions->MemberEnd(); json_extensions++)
+#endif
 
 mr_skip_extensions:
 
diff --git a/code/AssetLib/glTF/glTFAssetWriter.inl b/code/AssetLib/glTF/glTFAssetWriter.inl
index d8d2556fa..5b07eb2e9 100644
--- a/code/AssetLib/glTF/glTFAssetWriter.inl
+++ b/code/AssetLib/glTF/glTFAssetWriter.inl
@@ -305,11 +305,11 @@ namespace glTF {
 			Value json_extensions;
 
 			json_extensions.SetObject();
+#ifdef ASSIMP_IMPORTER_GLTF_USE_OPEN3DGC
 			for(Mesh::SExtension* ptr_ext : m.Extension)
 			{
 				switch(ptr_ext->Type)
 				{
-#ifdef ASSIMP_IMPORTER_GLTF_USE_OPEN3DGC
 					case Mesh::SExtension::EType::Compression_Open3DGC:
 						{
 							Value json_comp_data;
@@ -339,11 +339,11 @@ namespace glTF {
 						}
 
 						break;
-#endif
 					default:
 						throw DeadlyImportError("GLTF: Can not write mesh: unknown mesh extension, only Open3DGC is supported.");
 				}// switch(ptr_ext->Type)
 			}// for(Mesh::SExtension* ptr_ext : m.Extension)
+#endif
 
 			// Add extensions to mesh
 			obj.AddMember("extensions", json_extensions, w.mAl);
diff --git a/code/AssetLib/glTF/glTFImporter.cpp b/code/AssetLib/glTF/glTFImporter.cpp
index ef24592ae..c106acf21 100644
--- a/code/AssetLib/glTF/glTFImporter.cpp
+++ b/code/AssetLib/glTF/glTFImporter.cpp
@@ -215,8 +215,8 @@ void glTFImporter::ImportMeshes(glTF::Asset &r) {
 
         // Check if mesh extensions is used
         if (mesh.Extension.size() > 0) {
-            for (Mesh::SExtension *cur_ext : mesh.Extension) {
 #ifdef ASSIMP_IMPORTER_GLTF_USE_OPEN3DGC
+            for (Mesh::SExtension *cur_ext : mesh.Extension) {
                 if (cur_ext->Type == Mesh::SExtension::EType::Compression_Open3DGC) {
                     // Limitations for meshes when using Open3DGC-compression.
                     // It's a current limitation of sp... Specification have not this part still - about mesh compression. Why only one primitive?
@@ -233,12 +233,12 @@ void glTFImporter::ImportMeshes(glTF::Asset &r) {
 
                     buf->EncodedRegion_SetCurrent(mesh.id);
                 } else
-#endif
                 {
                     throw DeadlyImportError("GLTF: Can not import mesh: unknown mesh extension (code: \"" + to_string(cur_ext->Type) +
                                             "\"), only Open3DGC is supported.");
                 }
             }
+#endif
         } // if(mesh.Extension.size() > 0)
 
         meshOffsets.push_back(k);
diff --git a/code/CMakeLists.txt b/code/CMakeLists.txt
index 9f8f519d9..bb43449e1 100644
--- a/code/CMakeLists.txt
+++ b/code/CMakeLists.txt
@@ -899,7 +899,7 @@ ENDIF()
 # utf8
 IF(ASSIMP_HUNTER_ENABLED)
   hunter_add_package(utf8)
-  find_package(utf8 CONFIG REQUIRED)
+  find_package(utf8cpp CONFIG REQUIRED)
 ELSE()
   # utf8 is header-only, so Assimp doesn't need to do anything.
 ENDIF()
@@ -1159,7 +1159,7 @@ IF(ASSIMP_HUNTER_ENABLED)
       minizip::minizip
       ZLIB::zlib
       RapidJSON::rapidjson
-      utf8::utf8
+      utf8cpp
       zip::zip
   )
 ELSE()
diff --git a/code/Common/BaseImporter.cpp b/code/Common/BaseImporter.cpp
index 47ff05f2f..bcea076be 100644
--- a/code/Common/BaseImporter.cpp
+++ b/code/Common/BaseImporter.cpp
@@ -343,7 +343,7 @@ std::string BaseImporter::GetExtension(const std::string &file) {
 }
 
 #ifdef ASSIMP_USE_HUNTER
-#include <utf8/utf8.h>
+#include <utf8.h>
 #else
 #include "../contrib/utf8cpp/source/utf8.h"
 #endif
diff --git a/code/Common/DefaultIOStream.cpp b/code/Common/DefaultIOStream.cpp
index 65edd1bdd..32f47ab07 100644
--- a/code/Common/DefaultIOStream.cpp
+++ b/code/Common/DefaultIOStream.cpp
@@ -100,7 +100,6 @@ size_t DefaultIOStream::Write(const void *pvBuffer,
         size_t pCount) {
     ai_assert(nullptr != pvBuffer);
     ai_assert(0 != pSize);
-    ai_assert(0 != pCount);
 
     return (mFile ? ::fwrite(pvBuffer, pSize, pCount, mFile) : 0);
 }