Bug: https://bugs.gentoo.org/895052
--- a/cmake/CompileOptions.cmake
+++ b/cmake/CompileOptions.cmake
@@ -1,5 +1,5 @@
 # Set compiler flags
-set(CMAKE_C_STANDARD 99)
+set(CMAKE_C_STANDARD 11)
 set(CMAKE_C_STANDARD_REQUIRED ON)
 
 # analogous to AC_USE_SYSTEM_EXTENSIONS in configure.ac