diff --git a/src/web_service/CMakeLists.txt b/src/web_service/CMakeLists.txt
index 1c83e9c34b..9ad75e74a1 100644
--- a/src/web_service/CMakeLists.txt
+++ b/src/web_service/CMakeLists.txt
@@ -12,5 +12,5 @@ create_target_directory_groups(web_service)
 get_directory_property(OPENSSL_LIBS
         DIRECTORY ${CMAKE_SOURCE_DIR}/externals/libressl
         DEFINITION OPENSSL_LIBS)
-target_compile_definitions(web_service PUBLIC -DCPPHTTPLIB_OPENSSL_SUPPORT)
+target_compile_definitions(web_service PRIVATE -DCPPHTTPLIB_OPENSSL_SUPPORT)
 target_link_libraries(web_service PRIVATE common json-headers ${OPENSSL_LIBS} httplib lurlparser)