diff --git a/configure b/configure
index 92632e24d8..695fdb680d 100755
--- a/configure
+++ b/configure
@@ -167,7 +167,7 @@ else
 fi
 
 for opt do
-  optarg=`expr "$opt" : '[^=]*=\(.*\)'`
+  optarg=`expr "x$opt" : 'x[^=]*=\(.*\)'`
   case "$opt" in
   --help|-h) show_help=yes
   ;;