diff --git a/src/osgPlugins/png/ReaderWriterPNG.cpp b/src/osgPlugins/png/ReaderWriterPNG.cpp
index d0aee3d9e..75e008c7a 100644
--- a/src/osgPlugins/png/ReaderWriterPNG.cpp
+++ b/src/osgPlugins/png/ReaderWriterPNG.cpp
@@ -10,6 +10,7 @@ using namespace osg;
 
 extern "C"
 {
+    #include <zlib.h>
     #include <png.h>
 }