diff --git a/plugins/input/geojson/geojson_datasource.cpp b/plugins/input/geojson/geojson_datasource.cpp
index 06a20e736..7cafc55de 100644
--- a/plugins/input/geojson/geojson_datasource.cpp
+++ b/plugins/input/geojson/geojson_datasource.cpp
@@ -42,6 +42,7 @@
 #include <mapnik/projection.hpp>
 #include <mapnik/util/geometry_to_ds_type.hpp>
 #include <mapnik/util/variant.hpp>
+#include <mapnik/util/file_io.hpp>
 #include <mapnik/json/feature_collection_grammar.hpp>
 
 #include <boost/spirit/include/qi.hpp>
@@ -126,21 +127,14 @@ geojson_datasource::geojson_datasource(parameters const& params)
     }
     else
     {
-#ifdef _WINDOWS
-        std::unique_ptr<std::FILE, int (*)(std::FILE *)> file(_wfopen(mapnik::utf8_to_utf16(filename_).c_str(), L"rb"), fclose);
-#else
-        std::unique_ptr<std::FILE, int (*)(std::FILE *)> file(std::fopen(filename_.c_str(),"rb"), std::fclose);
-#endif
-        if (file == nullptr)
+        mapnik::util::file file(filename_);
+        if (!file.open())
         {
-            throw mapnik::datasource_exception("GeoJSON Plugin: could not open: '" + filename_ + "'");
+            throw mapnik::datasource_exception("TopoJSON Plugin: could not open: '" + filename_ + "'");
         }
-        std::fseek(file.get(), 0, SEEK_END);
-        std::size_t file_size = std::ftell(file.get());
-        std::fseek(file.get(), 0, SEEK_SET);
         std::string file_buffer;
-        file_buffer.resize(file_size);
-        std::fread(&file_buffer[0], file_size, 1, file.get());
+        file_buffer.resize(file.size());
+        std::fread(&file_buffer[0], file.size(), 1, file.get());
         parse_geojson(file_buffer);
     }
 }
diff --git a/plugins/input/topojson/topojson_datasource.cpp b/plugins/input/topojson/topojson_datasource.cpp
index 68c3e7f6e..341390902 100644
--- a/plugins/input/topojson/topojson_datasource.cpp
+++ b/plugins/input/topojson/topojson_datasource.cpp
@@ -37,6 +37,7 @@
 #include <mapnik/json/topojson_grammar_impl.hpp>
 #include <mapnik/json/topojson_utils.hpp>
 #include <mapnik/util/variant.hpp>
+#include <mapnik/util/file_io.hpp>
 #include <mapnik/make_unique.hpp>
 
 using mapnik::datasource;
@@ -170,21 +171,14 @@ topojson_datasource::topojson_datasource(parameters const& params)
     }
     else
     {
-#ifdef _WINDOWS
-        std::unique_ptr<std::FILE, int (*)(std::FILE *)> file(_wfopen(mapnik::utf8_to_utf16(filename_).c_str(), L"rb"), fclose);
-#else
-        std::unique_ptr<std::FILE, int (*)(std::FILE *)> file(std::fopen(filename_.c_str(),"rb"), std::fclose);
-#endif
-        if (file == nullptr)
+        mapnik::util::file file(filename_);
+        if (!file.open())
         {
             throw mapnik::datasource_exception("TopoJSON Plugin: could not open: '" + filename_ + "'");
         }
-        std::fseek(file.get(), 0, SEEK_END);
-        std::size_t file_size = std::ftell(file.get());
-        std::fseek(file.get(), 0, SEEK_SET);
         std::string file_buffer;
-        file_buffer.resize(file_size);
-        std::fread(&file_buffer[0], file_size, 1, file.get());
+        file_buffer.resize(file.size());
+        std::fread(&file_buffer[0], file.size(), 1, file.get());
         parse_topojson(file_buffer);
     }
 }