diff --git a/CMakeLists.txt b/CMakeLists.txt
index e403aea..43a4ac1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,7 +3,7 @@ cmake_minimum_required(VERSION 3.0)
 project(img4dc)
 
 ADD_DEFINITIONS("-Wall -Wpedantic")
-SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=c99")
+SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=gnu99")
 
 add_subdirectory(common)
 add_subdirectory(edc)