diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 80ee96913..bdcb25d06 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -100,6 +100,8 @@ set_target_properties(glfw PROPERTIES
                       POSITION_INDEPENDENT_CODE ON
                       FOLDER "GLFW3")
 
+target_compile_features(glfw PRIVATE c_std_99)
+
 target_compile_definitions(glfw PRIVATE _GLFW_USE_CONFIG_H)
 target_include_directories(glfw PUBLIC
                            "$<BUILD_INTERFACE:${GLFW_SOURCE_DIR}/include>"