diff --git a/simgear/io/lowlevel.hxx b/simgear/io/lowlevel.hxx
index b01b9f1a..0bc84aa9 100644
--- a/simgear/io/lowlevel.hxx
+++ b/simgear/io/lowlevel.hxx
@@ -29,7 +29,12 @@
 
 
 #include <stdio.h>
-#include <zlib.h>
+
+#ifdef HAVE_ZLIB
+#  include <zlib.h>
+#else
+#  include <simgear/zlib/zlib.h>
+#endif
 
 #include <plib/sg.h>
 
diff --git a/simgear/io/sg_binobj.cxx b/simgear/io/sg_binobj.cxx
index f68fb5d3..0e7082d0 100644
--- a/simgear/io/sg_binobj.cxx
+++ b/simgear/io/sg_binobj.cxx
@@ -30,7 +30,6 @@
 
 #include <stdio.h>
 #include <time.h>
-#include <zlib.h>
 
 #include <vector>
 #include STL_STRING