diff --git a/build-cmake/CMakeLists.txt b/build-cmake/CMakeLists.txt
index 379dd1a..6dbf193 100644
--- a/build-cmake/CMakeLists.txt
+++ b/build-cmake/CMakeLists.txt
@@ -9,7 +9,6 @@ CMAKE_MINIMUM_REQUIRED(VERSION 3.10 FATAL_ERROR)
 PROJECT(protobuf-c)
 
 #options
-option(BUILD_PROTO3 "BUILD_PROTO3" ON)
 option(BUILD_PROTOC "Build protoc-gen-c" ON)
 if(CMAKE_BUILD_TYPE MATCHES Debug)
 option(BUILD_TESTS "Build tests" ON)
@@ -73,9 +72,6 @@ endif (MSVC AND NOT BUILD_SHARED_LIBS)
 FIND_PACKAGE(Protobuf REQUIRED)
 INCLUDE_DIRECTORIES(${PROTOBUF_INCLUDE_DIR})
 
-if (BUILD_PROTO3)
-	ADD_DEFINITIONS(-DHAVE_PROTO3)
-endif()
 ENDIF()
 
 if (MSVC AND NOT BUILD_SHARED_LIBS)