diff --git a/m4/ax_append_to_file.m4 b/m4/ax_append_to_file.m4
index f9f54e088..15395178c 100644
--- a/m4/ax_append_to_file.m4
+++ b/m4/ax_append_to_file.m4
@@ -23,5 +23,5 @@
 
 AC_DEFUN([AX_APPEND_TO_FILE],[
 AC_REQUIRE([AX_FILE_ESCAPES])
-printf "$2\n" >> "$1"
+printf -- "$2\n" >> "$1"
 ])