diff --git a/scripts/check-padding b/scripts/check-padding
new file mode 100755
index 000000000..b10d34b73
--- /dev/null
+++ b/scripts/check-padding
@@ -0,0 +1,63 @@
+#!/usr/bin/env bash
+
+set -eu
+set -o pipefail
+
+cpp="/tmp/alignment.cpp"
+app="/tmp/alignment"
+
+function usage() {
+    echo "Usage:"
+    echo ""
+    echo "./scripts/rebuild.sh [header] [class name]"
+    echo ""
+    echo "Please pass a header file and a class name"
+    echo ""
+    echo "    ./scripts/check-padding include/mapnik/attribute.hpp mapnik::attribute"
+    echo ""
+    exit 1
+
+}
+
+function add() {
+    echo $1 >> ${cpp}
+}
+
+CXX=${CXX:-clang++}
+
+function compile() {
+    ${CXX} -o ${app} ${cpp} -Wpadded -I./ -isystem ./mason_packages/.link/include `mapnik-config --all-flags` -Ideps -Lsrc -Ideps/agg/include -Iinclude
+}
+
+if [[ ${1:-unset} == "unset" ]] || [[ ${2:-unset} == "unset" ]] || [[ $@ == '-h' ]] || [[ $@ == '--help' ]]; then
+    usage
+fi
+
+echo '' > ${cpp}
+
+add "#include <iostream>"
+add "#include <vector>"
+
+add "#include \"$1\""
+
+add ""
+
+add '#define REPORT(type) std::clog << "sizeof(" #type ") " << sizeof(type) << "\n";'
+
+add "int main() {"
+add ""
+
+add "REPORT(std::string)"
+add "REPORT(unsigned int)"
+add "REPORT(int)"
+add "REPORT(bool)"
+add "REPORT(std::vector<double>)"
+add "REPORT(std::size_t)"
+
+add "REPORT($2)"
+
+add "return 0;"
+add "}"
+
+compile
+${app}
diff --git a/tests/data/json/escaped.geojson b/tests/data/json/escaped.geojson
index 0836c2838..6f1531846 100644
--- a/tests/data/json/escaped.geojson
+++ b/tests/data/json/escaped.geojson
@@ -3,7 +3,6 @@
     "features":
     [
         {
-            "type":"Feature",
             "geometry":
             {
                 "type":"Point",
@@ -24,7 +23,8 @@
                 "NOM_FR":"Qu\u00e9bec",
                 "object": {"value":{"type":"\u041c\u0430pni\u043a","array": [3,0,"x"]}},
                 "array" : [ [ [1], ["deux"]],[["\u0442\u0440\u0438","four","\u4e94"]]]
-            }
+            },
+            "type":"Feature"
         }
     ]
 }
diff --git a/tests/visual_tests/compare.py b/tests/visual_tests/compare.py
index 65720af1a..30ccfc260 100644
--- a/tests/visual_tests/compare.py
+++ b/tests/visual_tests/compare.py
@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 
 import mapnik
+import os
 from unittest import TestCase
 
 try:
@@ -8,28 +9,6 @@ try:
 except ImportError:
     import simplejson as json
 
-
-# returns true if pixels are not nearly identical
-def compare_pixels(pixel1, pixel2, alpha=True, pixel_threshold=0):
-    if pixel1 == pixel2:
-        return False
-    r_diff = abs((pixel1 & 0xff) - (pixel2 & 0xff))
-    g_diff = abs(((pixel1 >> 8) & 0xff) - ((pixel2 >> 8) & 0xff))
-    b_diff = abs(((pixel1 >> 16) & 0xff)- ((pixel2 >> 16) & 0xff))
-    if alpha:
-        a_diff = abs(((pixel1 >> 24) & 0xff) - ((pixel2 >> 24) & 0xff))
-        if(r_diff > pixel_threshold or
-           g_diff > pixel_threshold or
-           b_diff > pixel_threshold or
-           a_diff > pixel_threshold):
-            return True
-    else:
-        if(r_diff > pixel_threshold or
-           g_diff > pixel_threshold or
-           b_diff > pixel_threshold):
-            return True
-    return False
-
 # compare two images and return number of different pixels
 def compare(actual, expected, alpha=True):
     im1 = mapnik.Image.open(actual)
diff --git a/tests/visual_tests/test.py b/tests/visual_tests/test.py
index b8d69fa14..75549c0f7 100755
--- a/tests/visual_tests/test.py
+++ b/tests/visual_tests/test.py
@@ -7,6 +7,7 @@ import mapnik
 #mapnik.logger.set_severity(mapnik.severity_type.Debug)
 import shutil
 import os.path
+import os
 from compare import compare, compare_grids
 import platform
 import glob
@@ -27,9 +28,14 @@ defaults = {
     'grid': mapnik.has_grid_renderer()
 }
 
-cairo_threshold = 0
-agg_threshold = 0
-grid_threshold = 0
+if os.name == 'nt':
+    cairo_threshold = 10
+    agg_threshold = 0
+    grid_threshold = 0
+else:
+    cairo_threshold = 0
+    agg_threshold = 0
+    grid_threshold = 0
 
 def render_cairo(m, output, scale_factor):
     mapnik.render_to_file(m, output, 'ARGB32', scale_factor)