diff --git a/configure.ac b/configure.ac
index 54af30535..5ea280f26 100644
--- a/configure.ac
+++ b/configure.ac
@@ -242,6 +242,7 @@ if test $gl_gcc_warnings != no; then
   # For gnulib-tests, the set is slightly smaller still.
   nw=
   # It's not worth being this picky about test programs.
+  nw="$nw -Wmissing-variable-declarations"
   nw="$nw -Wsuggest-attribute=cold"
   nw="$nw -Wsuggest-attribute=const"
   nw="$nw -Wsuggest-attribute=format"