diff --git a/src/osgPlugins/CMakeLists.txt b/src/osgPlugins/CMakeLists.txt
index 4982847ce..277dbebd5 100644
--- a/src/osgPlugins/CMakeLists.txt
+++ b/src/osgPlugins/CMakeLists.txt
@@ -111,7 +111,7 @@ ENDIF()
 IF(GIFLIB_FOUND)
     ADD_PLUGIN_DIRECTORY(gif)
 ENDIF()
-IF(PNG_FOUND)
+IF(PNG_FOUND AND ZLIB_FOUND)
     ADD_PLUGIN_DIRECTORY(png)
 ENDIF()
 IF(TIFF_FOUND)