diff -urN a/runtime/CMakeLists.txt b/runtime/CMakeLists.txt
--- a/runtime/CMakeLists.txt
+++ b/runtime/CMakeLists.txt
@@ -51,27 +51,6 @@ else()
 
   if (utf8cpp_HEADER)
     include_directories(${utf8cpp_HEADER})
-  else()
-    include(${CMAKE_ROOT}/Modules/ExternalProject.cmake)
-    set(THIRDPARTY_DIR ${CMAKE_BINARY_DIR}/runtime/thirdparty)
-    set(UTFCPP_DIR ${THIRDPARTY_DIR}/utfcpp)
-    ExternalProject_Add(
-      utf8cpp
-      GIT_REPOSITORY        "https://github.com/nemtrif/utfcpp"
-      GIT_TAG               "v3.1.1"
-      SOURCE_DIR            ${UTFCPP_DIR}
-      UPDATE_DISCONNECTED   1
-      CMAKE_ARGS            -DCMAKE_INSTALL_PREFIX=${UTFCPP_DIR}/install -DUTF8_TESTS=off -DUTF8_SAMPLES=off
-      STEP_TARGETS          build)
-
-    include_directories(
-      ${UTFCPP_DIR}/install/include/utf8cpp
-      ${UTFCPP_DIR}/install/include/utf8cpp/utf8
-      )
-
-    add_dependencies(antlr4_shared utf8cpp)
-    add_dependencies(antlr4_static utf8cpp)
-    set(INSTALL_utf8cpp TRUE)
   endif()
 endif()