Fix typo
diff --git a/configure.ac b/configure.ac
index 1ec7242..a17e155 100644
--- a/configure.ac
+++ b/configure.ac
@@ -12,7 +12,7 @@
 
 case "${host_os}" in
     linux-gnu*)	HOST_OS="linux-gnu" ;;
-    *)		AC_MSG_ERROR([unkown host-os ${host_osx}]) ;;
+    *)		AC_MSG_ERROR([unkown host-os ${host_os}]) ;;
 esac
 AC_SUBST(HOST_OS)