diff --git a/configure.ac b/configure.ac
index 598f57364dfb1255536c81c5c1f4b66251efbd11..5cbe3616059f02779d80d809dfb8a44e41621fc2 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,4 +1,10 @@
 # Process this file with autoconf to produce a configure script.
+#
+# Make sure we use autoconf 2.60 to generate the "configure" script,
+# in case we want to commit it. Other than that, version 2.59 is
+# perfectly fine for our purposes, so people who want to modify
+# this file just have to remember to set the AC_PREREQ argument
+# to something that suits their needs.
 
 AC_PREREQ(2.60)