diff --git a/cmake/modules/c_flags.cmake b/cmake/modules/c_flags.cmake
index 44052bba8..6e22d4ff3 100644
--- a/cmake/modules/c_flags.cmake
+++ b/cmake/modules/c_flags.cmake
@@ -20,6 +20,7 @@ endfunction()
 add_cflag_if_supported("-Wall")
 add_cflag_if_supported("-Wextra")
 add_cflag_if_supported("-Wshadow")
+add_cflag_if_supported("-O")
 add_cflag_if_supported("-D_FORTIFY_SOURCE=2")
 add_cflag_if_supported("-fstrict-aliasing")
 add_cflag_if_supported("-Wundef")