diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1365a9aee..b0a64053e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,6 +1,7 @@
 cmake_minimum_required(VERSION 2.8.5)
 project(sway C)
 set(CMAKE_C_FLAGS "-g")
+set(CMAKE_C_STANDARD 99)
 set(CMAKE_RUNTIME_OUTPUT_DIRECTORY "bin/")
 add_definitions("-Wall -Wextra -Wno-unused-parameter")
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} ${PROJECT_SOURCE_DIR}/CMake)