diff --git a/configure b/configure
index 2f259996ae..3380c87432 100755
--- a/configure
+++ b/configure
@@ -540,7 +540,7 @@ filter(){
     pat=$1
     shift
     for v; do
-        eval "case $v in $pat) printf '%s ' $v ;; esac"
+        eval "case '$v' in $pat) printf '%s ' '$v' ;; esac"
     done
 }
 
@@ -548,7 +548,7 @@ filter_out(){
     pat=$1
     shift
     for v; do
-        eval "case $v in $pat) ;; *) printf '%s ' $v ;; esac"
+        eval "case '$v' in $pat) ;; *) printf '%s ' '$v' ;; esac"
     done
 }