diff --git a/test/acceptance/limits.js b/test/acceptance/limits.js
index e7e4a305..ef91dac4 100644
--- a/test/acceptance/limits.js
+++ b/test/acceptance/limits.js
@@ -292,7 +292,8 @@ describe('render limits', function() {
                                 if (err) {
                                     done(err);
                                 }
-                                assert.imageEqualsFile(res.body, './test/fixtures/render-timeout-fallback.png', 25,
+                                var referenceImagePath = './test/fixtures/render-timeout-fallback.png';
+                                assert.imageBufferIsSimilarToFile(res.body, referenceImagePath, 25,
                                     function(imgErr/*, similarity*/) {
                                         done(imgErr);
                                     }
diff --git a/test/acceptance/multilayer.js b/test/acceptance/multilayer.js
index acd13ddc..5375fc87 100644
--- a/test/acceptance/multilayer.js
+++ b/test/acceptance/multilayer.js
@@ -122,7 +122,7 @@ describe(suiteName, function() {
                       ' WHERE m.tabname = any ((SELECT tablenames from querytables)::regclass[])');
               }
 
-              assert.imageEqualsFile(res.body, 'test/fixtures/test_table_0_0_0_multilayer1.png',
+              assert.imageBufferIsSimilarToFile(res.body, 'test/fixtures/test_table_0_0_0_multilayer1.png',
                   IMAGE_EQUALS_HIGHER_TOLERANCE_PER_MIL, function(err/*, similarity*/) {
                       next(err);
                   }
@@ -404,7 +404,8 @@ describe(suiteName, function() {
                       ' WHERE m.tabname = any ((SELECT tablenames from querytables)::regclass[])');
               }
 
-              assert.imageEqualsFile(res.body, 'test/fixtures/test_multilayer_bbox.png', IMAGE_EQUALS_TOLERANCE_PER_MIL,
+              var referenceImagePath = 'test/fixtures/test_multilayer_bbox.png';
+              assert.imageBufferIsSimilarToFile(res.body, referenceImagePath, IMAGE_EQUALS_TOLERANCE_PER_MIL,
                 function(err/*, similarity*/) {
                   next(err);
               });
@@ -443,7 +444,8 @@ describe(suiteName, function() {
                       ' WHERE m.tabname = any ((SELECT tablenames from querytables)::regclass[])');
               }
 
-              assert.imageEqualsFile(res.body, 'test/fixtures/test_multilayer_bbox.png', IMAGE_EQUALS_TOLERANCE_PER_MIL,
+              var referenceImagePath = 'test/fixtures/test_multilayer_bbox.png';
+              assert.imageBufferIsSimilarToFile(res.body, referenceImagePath, IMAGE_EQUALS_TOLERANCE_PER_MIL,
                 function(err/*, similarity*/) {
                   next(err);
               });
@@ -1019,7 +1021,7 @@ describe(suiteName, function() {
           }, {}, function(res) {
               assert.equal(res.statusCode, 200, res.body);
               assert.equal(res.headers['content-type'], "image/png");
-              assert.imageEqualsFile(res.body, windshaft_fixtures + '/test_default_mapnik_point.png',
+              assert.imageBufferIsSimilarToFile(res.body, windshaft_fixtures + '/test_default_mapnik_point.png',
                   IMAGE_EQUALS_TOLERANCE_PER_MIL, function(err/*, similarity*/) {
                       next(err);
                   }
diff --git a/test/acceptance/overviews_queries.js b/test/acceptance/overviews_queries.js
index 8024ba72..0434ebfc 100644
--- a/test/acceptance/overviews_queries.js
+++ b/test/acceptance/overviews_queries.js
@@ -30,7 +30,8 @@ describe('overviews_queries', function() {
             if (err) {
                 return done(err);
             }
-            assert.imageEqualsFile(tile.body, './test/fixtures/' + fixture, IMAGE_EQUALS_TOLERANCE_PER_MIL, done);
+            var referenceImagePath = './test/fixtures/' + fixture;
+            assert.imageBufferIsSimilarToFile(tile.body, referenceImagePath, IMAGE_EQUALS_TOLERANCE_PER_MIL, done);
         };
     }
 
diff --git a/test/acceptance/ported/blend.js b/test/acceptance/ported/blend.js
index eca436ae..1e844d80 100644
--- a/test/acceptance/ported/blend.js
+++ b/test/acceptance/ported/blend.js
@@ -95,10 +95,12 @@ describe('blend png renderer', function() {
         var zxy = [tileRequest.z, tileRequest.x, tileRequest.y];
         it('tile all/' + zxy.join('/') + '.png', function (done) {
             testClient.getTileLayer(plainTorqueMapConfig(testScenario.plainColor), tileRequest, function(err, res) {
-                assert.imageEqualsFile(res.body, blendPngFixture(zxy), IMAGE_TOLERANCE_PER_MIL, function(err) {
-                    assert.ok(!err);
-                    done();
-                });
+                assert.imageBufferIsSimilarToFile(res.body, blendPngFixture(zxy), IMAGE_TOLERANCE_PER_MIL,
+                    function(err) {
+                        assert.ok(!err);
+                        done();
+                    }
+                );
             });
         });
     });
diff --git a/test/acceptance/ported/blend_filtering.js b/test/acceptance/ported/blend_filtering.js
index c1b11933..dc8cd470 100644
--- a/test/acceptance/ported/blend_filtering.js
+++ b/test/acceptance/ported/blend_filtering.js
@@ -156,10 +156,12 @@ describe('blend layer filtering', function() {
 
         it('should filter on ' + layerFilter + '/1/0/0.png', function (done) {
             testClient.getTileLayer(mapConfig, tileRequest, function(err, res) {
-                assert.imageEqualsFile(res.body, blendPngFixture(filteredLayers), IMG_TOLERANCE_PER_MIL, function(err) {
-                    assert.ok(!err);
-                    done();
-                });
+                assert.imageBufferIsSimilarToFile(res.body, blendPngFixture(filteredLayers), IMG_TOLERANCE_PER_MIL,
+                    function(err) {
+                        assert.ok(!err);
+                        done();
+                    }
+                );
             });
         });
     });
diff --git a/test/acceptance/ported/blend_http_fallback.js b/test/acceptance/ported/blend_http_fallback.js
index 3c35c5fc..91e832f6 100644
--- a/test/acceptance/ported/blend_http_fallback.js
+++ b/test/acceptance/ported/blend_http_fallback.js
@@ -111,10 +111,12 @@ describe('blend http fallback', function() {
 
         it('should fallback on http error while blending layers ' + layerFilter + '/1/0/0.png', function (done) {
             testClient.getTileLayer(mapConfig, tileRequest, function(err, res) {
-                assert.imageEqualsFile(res.body, blendPngFixture(filteredLayers), IMG_TOLERANCE_PER_MIL, function(err) {
-                    assert.ok(!err, err);
-                    done();
-                });
+                assert.imageBufferIsSimilarToFile(res.body, blendPngFixture(filteredLayers), IMG_TOLERANCE_PER_MIL,
+                    function(err) {
+                        assert.ok(!err, err);
+                        done();
+                    }
+                );
             });
         });
     });
diff --git a/test/acceptance/ported/external_resources.js b/test/acceptance/ported/external_resources.js
index a0affa83..6f73b52e 100644
--- a/test/acceptance/ported/external_resources.js
+++ b/test/acceptance/ported/external_resources.js
@@ -57,7 +57,8 @@ describe('external resources', function() {
             if (err) {
                 return done(err);
             }
-            assert.imageEqualsFile(res.body, './test/fixtures/' + fixture, IMAGE_EQUALS_TOLERANCE_PER_MIL, done);
+            var referenceImagePath = './test/fixtures/' + fixture;
+            assert.imageBufferIsSimilarToFile(res.body, referenceImagePath, IMAGE_EQUALS_TOLERANCE_PER_MIL, done);
         };
     }
 
diff --git a/test/acceptance/ported/limits.js b/test/acceptance/ported/limits.js
index f032ff3f..c111c87c 100644
--- a/test/acceptance/ported/limits.js
+++ b/test/acceptance/ported/limits.js
@@ -84,11 +84,13 @@ describe.skip('render limits', function() {
         testClient.withLayergroup(slowQueryMapConfig, options, function(err, requestTile, finish) {
             var tileUrl = '/0/0/0.png';
             requestTile(tileUrl, options, function(err, res) {
-                assert.imageEqualsFile(res.body, fixtureImage, IMAGE_EQUALS_TOLERANCE_PER_MIL, function(err) {
-                    finish(function(finishErr) {
-                        done(err || finishErr);
-                    });
-                });
+                assert.imageBufferIsSimilarToFile(res.body, fixtureImage, IMAGE_EQUALS_TOLERANCE_PER_MIL,
+                    function(err) {
+                        finish(function(finishErr) {
+                            done(err || finishErr);
+                        });
+                    }
+                );
             });
         });
     });
diff --git a/test/acceptance/ported/multilayer.js b/test/acceptance/ported/multilayer.js
index 7e9b984c..eb337070 100644
--- a/test/acceptance/ported/multilayer.js
+++ b/test/acceptance/ported/multilayer.js
@@ -117,7 +117,8 @@ describe('multilayer', function() {
               assert.equal(res.statusCode, 200, res.body);
               assert.equal(res.headers['content-type'], "image/png");
               checkCORSHeaders(res);
-              assert.imageEqualsFile(res.body, './test/fixtures/test_bigpoint_red.png', IMAGE_EQUALS_TOLERANCE_PER_MIL,
+              var referenceImagePath = './test/fixtures/test_bigpoint_red.png';
+              assert.imageBufferIsSimilarToFile(res.body, referenceImagePath, IMAGE_EQUALS_TOLERANCE_PER_MIL,
                   function(err) {
                   next(err);
               });
@@ -191,7 +192,8 @@ describe('multilayer', function() {
           }, {}, function(res) {
               assert.equal(res.statusCode, 200, res.body);
               assert.equal(res.headers['content-type'], "image/png");
-              assert.imageEqualsFile(res.body, './test/acceptance/ported/fixtures/test_table_0_0_0_multilayer1.png',
+              var referenceImagePath = './test/acceptance/ported/fixtures/test_table_0_0_0_multilayer1.png';
+              assert.imageBufferIsSimilarToFile(res.body, referenceImagePath,
                   IMAGE_EQUALS_TOLERANCE_PER_MIL, function(err) {
                   next(err);
               });
@@ -302,7 +304,8 @@ describe('multilayer', function() {
           }, {}, function(res) {
               assert.equal(res.statusCode, 200, res.body);
               assert.equal(res.headers['content-type'], "image/png");
-              assert.imageEqualsFile(res.body, './test/acceptance/ported/fixtures/test_table_0_0_0_multilayer1.png',
+              var referenceImagePath = './test/acceptance/ported/fixtures/test_table_0_0_0_multilayer1.png';
+              assert.imageBufferIsSimilarToFile(res.body, referenceImagePath,
                   IMAGE_EQUALS_TOLERANCE_PER_MIL, function(err) {
                   next(err);
               });
@@ -425,7 +428,8 @@ describe('multilayer', function() {
           }, {}, function(res) {
               assert.equal(res.statusCode, 200, res.body);
               assert.equal(res.headers['content-type'], "image/png");
-              assert.imageEqualsFile(res.body, './test/acceptance/ported/fixtures/test_table_0_0_0_multilayer1.png',
+              var referenceImagePath = './test/acceptance/ported/fixtures/test_table_0_0_0_multilayer1.png';
+              assert.imageBufferIsSimilarToFile(res.body, referenceImagePath,
                   IMAGE_EQUALS_TOLERANCE_PER_MIL, function(err) {
                   next(err);
               });
@@ -541,7 +545,8 @@ describe('multilayer', function() {
           }, {}, function(res) {
               assert.equal(res.statusCode, 200, res.body);
               assert.equal(res.headers['content-type'], "image/png");
-              assert.imageEqualsFile(res.body, './test/acceptance/ported/fixtures/test_table_0_0_0_multilayer1.png',
+              var referenceImagePath = './test/acceptance/ported/fixtures/test_table_0_0_0_multilayer1.png';
+              assert.imageBufferIsSimilarToFile(res.body, referenceImagePath,
                   IMAGE_EQUALS_TOLERANCE_PER_MIL, function(err) {
                   next(err);
               });
@@ -727,7 +732,8 @@ describe('multilayer', function() {
           }, {}, function(res) {
               assert.equal(res.statusCode, 200, res.body);
               assert.equal(res.headers['content-type'], "image/png");
-              assert.imageEqualsFile(res.body, './test/acceptance/ported/fixtures/test_table_0_0_0_multilayer2.png',
+              var referenceImagePath = './test/acceptance/ported/fixtures/test_table_0_0_0_multilayer2.png';
+              assert.imageBufferIsSimilarToFile(res.body, referenceImagePath,
                   IMAGE_EQUALS_TOLERANCE_PER_MIL, function(err) {
                   next(err);
               });
@@ -761,7 +767,8 @@ describe('multilayer', function() {
           }, {}, function(res) {
               assert.equal(res.statusCode, 200, res.body);
               assert.equal(res.headers['content-type'], "image/png");
-              assert.imageEqualsFile(res.body, './test/acceptance/ported/fixtures/test_table_0_0_0_multilayer3.png',
+              var referenceImagePath = './test/acceptance/ported/fixtures/test_table_0_0_0_multilayer3.png';
+              assert.imageBufferIsSimilarToFile(res.body, referenceImagePath,
                   IMAGE_EQUALS_TOLERANCE_PER_MIL, function(err) {
                   next(err);
               });
@@ -856,7 +863,8 @@ describe('multilayer', function() {
           }, {}, function(res) {
               assert.equal(res.statusCode, 200, res.body);
               assert.equal(res.headers['content-type'], "image/png");
-              assert.imageEqualsFile(res.body, './test/acceptance/ported/fixtures/test_table_0_0_0_multilayer4.png',
+              var referenceImagePath = './test/acceptance/ported/fixtures/test_table_0_0_0_multilayer4.png';
+              assert.imageBufferIsSimilarToFile(res.body, referenceImagePath,
                   IMAGE_EQUALS_TOLERANCE_PER_MIL, function(err) {
                   next(err);
               });
@@ -1259,7 +1267,7 @@ describe('multilayer', function() {
               assert.equal(res.statusCode, 200, res.body);
               assert.equal(res.headers['content-type'], "image/png");
               checkCORSHeaders(res);
-              assert.imageEqualsFile(res.body, './test/fixtures/test_bigpoint_red.png',
+              assert.imageBufferIsSimilarToFile(res.body, './test/fixtures/test_bigpoint_red.png',
                   IMAGE_EQUALS_TOLERANCE_PER_MIL, function(err) {
                   next(err);
               });
diff --git a/test/acceptance/ported/raster.js b/test/acceptance/ported/raster.js
index 00d34509..cd3d43b9 100644
--- a/test/acceptance/ported/raster.js
+++ b/test/acceptance/ported/raster.js
@@ -87,7 +87,7 @@ describe('raster', function() {
           assert.equal(res.statusCode, 200, res.body);
           assert.deepEqual(res.headers['content-type'], "image/png");
           var next = this;
-          assert.imageEqualsFile(res.body,
+          assert.imageBufferIsSimilarToFile(res.body,
             './test/fixtures/raster_gray_rect.png',
             IMAGE_EQUALS_TOLERANCE_PER_MIL, function(err) {
               try {
diff --git a/test/acceptance/ported/server_gettile.js b/test/acceptance/ported/server_gettile.js
index 7dad9aa3..580e8a61 100644
--- a/test/acceptance/ported/server_gettile.js
+++ b/test/acceptance/ported/server_gettile.js
@@ -34,7 +34,9 @@ describe('server_gettile', function() {
             if (err) {
                 return done(err);
             }
-            assert.imageEqualsFile(res.body, './test/fixtures/' + fixture, IMAGE_EQUALS_TOLERANCE_PER_MIL, done);
+            assert.imageBufferIsSimilarToFile(
+                res.body, './test/fixtures/' + fixture, IMAGE_EQUALS_TOLERANCE_PER_MIL, done
+            );
         };
     }
 
@@ -113,12 +115,13 @@ describe('server_gettile', function() {
                 assert.ok(res.headers.hasOwnProperty('x-windshaft-cache'), "Did not hit renderer cache on second time");
                 assert.ok(res.headers['x-windshaft-cache'] >= 0);
 
-                assert.imageEqualsFile(res.body, imageFixture, IMAGE_EQUALS_TOLERANCE_PER_MIL, function(err) {
-
-                    finish(function(finishErr) {
-                        done(err || finishErr);
-                    });
-                });
+                assert.imageBufferIsSimilarToFile(res.body, imageFixture, IMAGE_EQUALS_TOLERANCE_PER_MIL,
+                    function(err) {
+                        finish(function(finishErr) {
+                            done(err || finishErr);
+                        });
+                    }
+                );
             });
         });
     });
diff --git a/test/acceptance/ported/torque_png.js b/test/acceptance/ported/torque_png.js
index fef2c621..69eaadab 100644
--- a/test/acceptance/ported/torque_png.js
+++ b/test/acceptance/ported/torque_png.js
@@ -83,10 +83,12 @@ describe('torque png renderer', function() {
         var zxy = [z, x, y];
         it('tile ' + zxy.join('/') + '.torque.png', function (done) {
             testClient.getTileLayer(torquePngPointsMapConfig, tileRequest, function(err, res) {
-                assert.imageEqualsFile(res.body, torquePngFixture(zxy), IMAGE_TOLERANCE_PER_MIL, function(err) {
-                    assert.ok(!err);
-                    done();
-                });
+                assert.imageBufferIsSimilarToFile(res.body, torquePngFixture(zxy), IMAGE_TOLERANCE_PER_MIL,
+                    function(err) {
+                        assert.ok(!err);
+                        done();
+                    }
+                );
             });
         });
     });
diff --git a/test/acceptance/ported/wrap.js b/test/acceptance/ported/wrap.js
index 1f46b5c3..64a8e2f4 100644
--- a/test/acceptance/ported/wrap.js
+++ b/test/acceptance/ported/wrap.js
@@ -107,10 +107,12 @@ describe('wrap x coordinate', function() {
             var fixtureZxy = [testScenario.fixture.z, testScenario.fixture.x, testScenario.fixture.y];
             it('tile all/' + zxy.join('/') + '.png', function (done) {
                 testClient.getTileLayer(plainTorqueMapConfig(testScenario.plainColor), tileRequest, function(err, res) {
-                    assert.imageEqualsFile(res.body, blendPngFixture(fixtureZxy), IMG_TOLERANCE_PER_MIL, function(err) {
-                        assert.ok(!err);
-                        done();
-                    });
+                    assert.imageBufferIsSimilarToFile(res.body, blendPngFixture(fixtureZxy), IMG_TOLERANCE_PER_MIL,
+                        function(err) {
+                            assert.ok(!err);
+                            done();
+                        }
+                    );
                 });
             });
         });
diff --git a/test/support/assert.js b/test/support/assert.js
index 7cb363d1..36203d16 100644
--- a/test/support/assert.js
+++ b/test/support/assert.js
@@ -21,7 +21,7 @@ var assert = module.exports = exports = require('assert');
  * @param {function} callback Will call to home with null in case there is no error, otherwise with the error itself
  * @see FUZZY in http://www.imagemagick.org/script/command-line-options.php#metric
  */
-assert.imageEqualsFile = function(buffer, referenceImageRelativeFilePath, tolerance, callback) {
+assert.imageBufferIsSimilarToFile = function(buffer, referenceImageRelativeFilePath, tolerance, callback) {
     callback = callback || function(err) { assert.ifError(err); };
 
     var referenceImageFilePath = path.resolve(referenceImageRelativeFilePath);