diff --git a/configure.in b/configure.in
index f4d3e8b0df..ea34a78a94 100644
--- a/configure.in
+++ b/configure.in
@@ -164,6 +164,7 @@ fi
 case "${enable_shared}" in
   yes) shared=yes ;;
   no) shared=no ;;
+  "") shared=no ;;
   *) shared=yes ;;
 esac