diff --git a/auto.sh b/auto.sh
index 570dea3..fe3feef 100755
--- a/auto.sh
+++ b/auto.sh
@@ -41,7 +41,7 @@ if [ ! -f "lib/pcre/configure" ]; then
 fi
 
 ### ZLIB reconf
-if [ ! -f "lib/zlib-ng/configure" ]; then
+if [ -f "lib/zlib-ng/configure" ]; then
     cd lib/zlib-ng
     ./configure
     cd ../..