diff --git a/m4/.gitignore b/m4/.gitignore
index 01a2a593d0..63f9fa78ed 100644
--- a/m4/.gitignore
+++ b/m4/.gitignore
@@ -3,6 +3,7 @@
 
 !ax_compare_version.m4
 !ax_cxx_compile_stdcxx.m4
+!ax_lua.m4
 !ax_prog_perl_modules.m4
 !ax_pthread.m4
 !ax_python.m4