diff --git a/src/configure.ac b/src/configure.ac
index 062c75a..22c280d 100644
--- a/src/configure.ac
+++ b/src/configure.ac
@@ -632,7 +632,7 @@
 	  inc_path="$vi_cv_path_lua_pfx/include"
 	  for dir in "$inc_path"/moonjit-[[0-9]]* ; do
 	    if test -d "$dir" ; then
-	      lua_suf=`basename '$dir'`
+	      lua_suf=`basename "$dir"`
 	      lua_suf="/$lua_suf"
 	      break
 	    fi