diff --git a/Modules/Core/Common/include/itkCommonEnums.h b/Modules/Core/Common/include/itkCommonEnums.h
index 127275afd9c..b57bd025f52 100644
--- a/Modules/Core/Common/include/itkCommonEnums.h
+++ b/Modules/Core/Common/include/itkCommonEnums.h
@@ -71,6 +71,8 @@ class CommonEnums
    * Enums used to manipulate the component type. The component type
    * refers to the actual storage class associated with either a
    * SCALAR pixel type or elements of a compound pixel.
+   *
+   * \note The enum `CHAR` represents `signed char` (not just plain `char`).
    */
   ITK_CLANG_PRAGMA_PUSH
   ITK_CLANG_SUPPRESS_Wduplicate_enum
diff --git a/Modules/Core/TestKernel/src/itkTestDriverInclude.cxx b/Modules/Core/TestKernel/src/itkTestDriverInclude.cxx
index 340c4f708b9..ed627dde194 100644
--- a/Modules/Core/TestKernel/src/itkTestDriverInclude.cxx
+++ b/Modules/Core/TestKernel/src/itkTestDriverInclude.cxx
@@ -828,7 +828,7 @@ HashTestImage(const char * testImageFilename, const std::vector<std::string> & b
   switch (componentType)
   {
     case itk::IOComponentEnum::CHAR:
-      testMD5 = ComputeHash<itk::VectorImage<char, ITK_TEST_DIMENSION_MAX>>(testImageFilename);
+      testMD5 = ComputeHash<itk::VectorImage<signed char, ITK_TEST_DIMENSION_MAX>>(testImageFilename);
       break;
     case itk::IOComponentEnum::UCHAR:
       testMD5 = ComputeHash<itk::VectorImage<unsigned char, ITK_TEST_DIMENSION_MAX>>(testImageFilename);
diff --git a/Modules/IO/ImageBase/include/itkImageFileReader.hxx b/Modules/IO/ImageBase/include/itkImageFileReader.hxx
index 78b4207f03e..ba4b27151a2 100644
--- a/Modules/IO/ImageBase/include/itkImageFileReader.hxx
+++ b/Modules/IO/ImageBase/include/itkImageFileReader.hxx
@@ -482,7 +482,7 @@ ImageFileReader<TOutputImage, ConvertPixelTraits>::DoConvertBuffer(const void *
   {
   }
   ITK_CONVERT_BUFFER_IF_BLOCK(IOComponentEnum::UCHAR, unsigned char)
-  ITK_CONVERT_BUFFER_IF_BLOCK(IOComponentEnum::CHAR, char)
+  ITK_CONVERT_BUFFER_IF_BLOCK(IOComponentEnum::CHAR, signed char)
   ITK_CONVERT_BUFFER_IF_BLOCK(IOComponentEnum::USHORT, unsigned short)
   ITK_CONVERT_BUFFER_IF_BLOCK(IOComponentEnum::SHORT, short)
   ITK_CONVERT_BUFFER_IF_BLOCK(IOComponentEnum::UINT, unsigned int)
diff --git a/Modules/IO/ImageBase/src/itkImageIOBase.cxx b/Modules/IO/ImageBase/src/itkImageIOBase.cxx
index 76737643537..c2c4022600b 100644
--- a/Modules/IO/ImageBase/src/itkImageIOBase.cxx
+++ b/Modules/IO/ImageBase/src/itkImageIOBase.cxx
@@ -824,7 +824,7 @@ ImageIOBase::ReadBufferAsASCII(std::istream & is, void * buffer, IOComponentEnum
     break;
     case IOComponentEnum::CHAR:
     {
-      auto * buf = static_cast<char *>(buffer);
+      auto * buf = static_cast<signed char *>(buffer);
       ReadBuffer(is, buf, numComp);
     }
     break;
diff --git a/Modules/IO/MeshBase/include/itkMeshFileReader.hxx b/Modules/IO/MeshBase/include/itkMeshFileReader.hxx
index f95533631b5..5d0d6ca0472 100644
--- a/Modules/IO/MeshBase/include/itkMeshFileReader.hxx
+++ b/Modules/IO/MeshBase/include/itkMeshFileReader.hxx
@@ -703,7 +703,7 @@ MeshFileReader<TOutputMesh, ConvertPointPixelTraits, ConvertCellPixelTraits>::Co
   {
   }
   ITK_CONVERT_POINT_PIXEL_BUFFER_IF_BLOCK(IOComponentEnum::UCHAR, unsigned char)
-  ITK_CONVERT_POINT_PIXEL_BUFFER_IF_BLOCK(IOComponentEnum::CHAR, char)
+  ITK_CONVERT_POINT_PIXEL_BUFFER_IF_BLOCK(IOComponentEnum::CHAR, signed char)
   ITK_CONVERT_POINT_PIXEL_BUFFER_IF_BLOCK(IOComponentEnum::USHORT, unsigned short)
   ITK_CONVERT_POINT_PIXEL_BUFFER_IF_BLOCK(IOComponentEnum::SHORT, short)
   ITK_CONVERT_POINT_PIXEL_BUFFER_IF_BLOCK(IOComponentEnum::UINT, unsigned int)
@@ -778,7 +778,7 @@ MeshFileReader<TOutputMesh, ConvertPointPixelTraits, ConvertCellPixelTraits>::Co
   {
   }
   ITK_CONVERT_CELL_PIXEL_BUFFER_IF_BLOCK(IOComponentEnum::UCHAR, unsigned char)
-  ITK_CONVERT_CELL_PIXEL_BUFFER_IF_BLOCK(IOComponentEnum::CHAR, char)
+  ITK_CONVERT_CELL_PIXEL_BUFFER_IF_BLOCK(IOComponentEnum::CHAR, signed char)
   ITK_CONVERT_CELL_PIXEL_BUFFER_IF_BLOCK(IOComponentEnum::USHORT, unsigned short)
   ITK_CONVERT_CELL_PIXEL_BUFFER_IF_BLOCK(IOComponentEnum::SHORT, short)
   ITK_CONVERT_CELL_PIXEL_BUFFER_IF_BLOCK(IOComponentEnum::UINT, unsigned int)
diff --git a/Modules/IO/TIFF/test/itkTIFFImageIOCompressionTest.cxx b/Modules/IO/TIFF/test/itkTIFFImageIOCompressionTest.cxx
index 939ca44cc9c..7cff904d43c 100644
--- a/Modules/IO/TIFF/test/itkTIFFImageIOCompressionTest.cxx
+++ b/Modules/IO/TIFF/test/itkTIFFImageIOCompressionTest.cxx
@@ -200,7 +200,7 @@ itkTIFFImageIOCompressionTest(int argc, char * argv[])
         }
         case itk::IOComponentEnum::CHAR:
         {
-          using PixelType = char;
+          using PixelType = signed char;
           return itkTIFFImageIOCompressionTestHelper<itk::Image<PixelType, 2>>(argc, argv, JPEGQuality);
         }
         case itk::IOComponentEnum::USHORT:
diff --git a/Modules/Video/IO/include/itkVideoFileReader.hxx b/Modules/Video/IO/include/itkVideoFileReader.hxx
index d4d3199c434..f0c52feaac5 100644
--- a/Modules/Video/IO/include/itkVideoFileReader.hxx
+++ b/Modules/Video/IO/include/itkVideoFileReader.hxx
@@ -274,7 +274,7 @@ VideoFileReader<TOutputVideoStream>::DoConvertBuffer(const void * inputData, Fra
   {
   }
   ITK_CONVERT_BUFFER_IF_BLOCK(IOComponentEnum::UCHAR, unsigned char)
-  ITK_CONVERT_BUFFER_IF_BLOCK(IOComponentEnum::CHAR, char)
+  ITK_CONVERT_BUFFER_IF_BLOCK(IOComponentEnum::CHAR, signed char)
   ITK_CONVERT_BUFFER_IF_BLOCK(IOComponentEnum::USHORT, unsigned short)
   ITK_CONVERT_BUFFER_IF_BLOCK(IOComponentEnum::SHORT, short)
   ITK_CONVERT_BUFFER_IF_BLOCK(IOComponentEnum::UINT, unsigned int)