diff --git a/plugins/input/geojson/geojson_datasource.cpp b/plugins/input/geojson/geojson_datasource.cpp
index 774c8d248..b6c6fa609 100644
--- a/plugins/input/geojson/geojson_datasource.cpp
+++ b/plugins/input/geojson/geojson_datasource.cpp
@@ -133,7 +133,7 @@ geojson_datasource::geojson_datasource(parameters const& params)
     else
     {
         cache_features_ = *params.get<mapnik::boolean_type>("cache_features", true);
-#if defined(SHAPE_MEMORY_MAPPED_FILE)
+#if !defined(SHAPE_MEMORY_MAPPED_FILE)
         mapnik::util::file file(filename_);
         if (!file.open())
         {