diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5238f33..55c9c84 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -20,10 +20,6 @@ option(TINYGLTF_INSTALL "Install tinygltf files during install step. Usually set
 option(TINYGLTF_INSTALL_VENDOR "Install vendored nlohmann/json and nothings/stb headers" ON)
 option(TINYGLTF_USE_CUSTOM_JSON "Use the built-in fast JSON parser (tinygltf_json.h) instead of nlohmann/json" OFF)
 
-if (TINYGLTF_USE_CUSTOM_JSON)
-  add_definitions(-DTINYGLTF_USE_CUSTOM_JSON)
-endif (TINYGLTF_USE_CUSTOM_JSON)
-
 if (TINYGLTF_BUILD_LOADER_EXAMPLE)
   add_executable(loader_example
     loader_example.cc
@@ -76,6 +72,14 @@ else (TINYGLTF_HEADER_ONLY)
           )
 endif (TINYGLTF_HEADER_ONLY)
 
+if (TINYGLTF_USE_CUSTOM_JSON)
+  if (TINYGLTF_HEADER_ONLY)
+    target_compile_definitions(tinygltf INTERFACE TINYGLTF_USE_CUSTOM_JSON)
+  else ()
+    target_compile_definitions(tinygltf PUBLIC TINYGLTF_USE_CUSTOM_JSON)
+  endif ()
+endif ()
+
 if (TINYGLTF_INSTALL)
   install(TARGETS tinygltf EXPORT tinygltfTargets)
   install(EXPORT tinygltfTargets NAMESPACE tinygltf:: FILE TinyGLTFTargets.cmake DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/tinygltf)