--- configure.ac	2015-05-10 14:24:44.000000000 +0200
+++ configure.ac.new	2015-05-31 09:39:22.617867000 +0200
@@ -120,7 +120,7 @@
     extra_libs="zlib/libz.a"
     mkdir -p zlib
 else
-    extra_ldflags="-lz"
+    extra_libs="-lz"
 fi
 
 dnl Linking on Windows needs ws2_32