diff --git a/CMake/itkCompilerChecks.cmake b/CMake/itkCompilerChecks.cmake
index 6a41860130c..da1be82a20b 100644
--- a/CMake/itkCompilerChecks.cmake
+++ b/CMake/itkCompilerChecks.cmake
@@ -38,3 +38,12 @@ if(NOT ITK_IGNORE_CMAKE_CXX17_CHECKS)
     set(CMAKE_CXX_EXTENSIONS OFF)
   endif()
 endif()
+
+# MSVC does not set __cplusplus correctly by default (returns 199711L
+# regardless of the actual standard). /Zc:__cplusplus makes it report
+# the true value. Required for third-party headers (e.g. DCMTK
+# osconfig.h) that check __cplusplus >= 201103L at compile time.
+# Available since VS2017 15.7 (MSVC 19.14); we require 19.20+.
+if(MSVC AND NOT CMAKE_CXX_FLAGS MATCHES "/Zc:__cplusplus")
+  string(APPEND CMAKE_CXX_FLAGS " /Zc:__cplusplus")
+endif()
diff --git a/Modules/ThirdParty/DCMTK/CMakeLists.txt b/Modules/ThirdParty/DCMTK/CMakeLists.txt
index 5aaf18f2ebf..f4b4c6c7217 100644
--- a/Modules/ThirdParty/DCMTK/CMakeLists.txt
+++ b/Modules/ThirdParty/DCMTK/CMakeLists.txt
@@ -130,7 +130,13 @@ else(ITK_USE_SYSTEM_DCMTK)
   set(ITKDCMTK_LIBRARIES "${_ITKDCMTK_LIB_NAMES}")
   #
   # add all the embedded include directories to include dirs
+  # Skip internal JPEG codec libraries (ijg8, ijg12, ijg16) — they have
+  # no public headers and exporting non-existent paths in
+  # INTERFACE_INCLUDE_DIRECTORIES causes CMake errors in external modules.
   foreach(lib ${_ITKDCMTK_LIB_NAMES})
+    if(lib MATCHES "^ijg")
+      continue()
+    endif()
     # add to include list
     list(APPEND ITKDCMTK_INCLUDE_DIRS
       ${ITKDCMTK_INCLUDE}/${lib}/include)