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diff --git a/test/unit/modulate.js b/test/unit/modulate.js
index c187b48a..8cd6b5ab 100644
--- a/test/unit/modulate.js
+++ b/test/unit/modulate.js
@@ -28,115 +28,138 @@ describe('Modulate', function () {
     });
   });
 
-  it('should be able to hue-rotate', function () {
-    const base = 'modulate-hue-120.jpg';
-    const actual = fixtures.path('output.' + base);
-    const expected = fixtures.expected(base);
-
-    return sharp(fixtures.inputJpg)
+  it('should be able to hue-rotate', async () => {
+    const [r, g, b] = await sharp({
+      create: {
+        width: 1,
+        height: 1,
+        channels: 3,
+        background: { r: 153, g: 68, b: 68 }
+      }
+    })
       .modulate({ hue: 120 })
-      .toFile(actual)
-      .then(function () {
-        fixtures.assertMaxColourDistance(actual, expected, 25);
-      });
+      .raw()
+      .toBuffer();
+
+    assert.deepStrictEqual({ r: 41, g: 107, b: 57 }, { r, g, b });
   });
 
-  it('should be able to brighten', function () {
-    const base = 'modulate-brightness-2.jpg';
-    const actual = fixtures.path('output.' + base);
-    const expected = fixtures.expected(base);
-
-    return sharp(fixtures.inputJpg)
+  it('should be able to brighten', async () => {
+    const [r, g, b] = await sharp({
+      create: {
+        width: 1,
+        height: 1,
+        channels: 3,
+        background: { r: 153, g: 68, b: 68 }
+      }
+    })
       .modulate({ brightness: 2 })
-      .toFile(actual)
-      .then(function () {
-        fixtures.assertMaxColourDistance(actual, expected, 25);
-      });
+      .raw()
+      .toBuffer();
+
+    assert.deepStrictEqual({ r: 255, g: 173, b: 168 }, { r, g, b });
   });
 
-  it('should be able to unbrighten', function () {
-    const base = 'modulate-brightness-0-5.jpg';
-    const actual = fixtures.path('output.' + base);
-    const expected = fixtures.expected(base);
-
-    return sharp(fixtures.inputJpg)
+  it('should be able to darken', async () => {
+    const [r, g, b] = await sharp({
+      create: {
+        width: 1,
+        height: 1,
+        channels: 3,
+        background: { r: 153, g: 68, b: 68 }
+      }
+    })
       .modulate({ brightness: 0.5 })
-      .toFile(actual)
-      .then(function () {
-        fixtures.assertMaxColourDistance(actual, expected, 25);
-      });
+      .raw()
+      .toBuffer();
+
+    assert.deepStrictEqual({ r: 97, g: 17, b: 25 }, { r, g, b });
   });
 
-  it('should be able to saturate', function () {
-    const base = 'modulate-saturation-2.jpg';
-    const actual = fixtures.path('output.' + base);
-    const expected = fixtures.expected(base);
-
-    return sharp(fixtures.inputJpg)
+  it('should be able to saturate', async () => {
+    const [r, g, b] = await sharp({
+      create: {
+        width: 1,
+        height: 1,
+        channels: 3,
+        background: { r: 153, g: 68, b: 68 }
+      }
+    })
       .modulate({ saturation: 2 })
-      .toFile(actual)
-      .then(function () {
-        fixtures.assertMaxColourDistance(actual, expected, 30);
-      });
+      .raw()
+      .toBuffer();
+
+    assert.deepStrictEqual({ r: 198, g: 0, b: 43 }, { r, g, b });
   });
 
-  it('should be able to desaturate', function () {
-    const base = 'modulate-saturation-0.5.jpg';
-    const actual = fixtures.path('output.' + base);
-    const expected = fixtures.expected(base);
-
-    return sharp(fixtures.inputJpg)
+  it('should be able to desaturate', async () => {
+    const [r, g, b] = await sharp({
+      create: {
+        width: 1,
+        height: 1,
+        channels: 3,
+        background: { r: 153, g: 68, b: 68 }
+      }
+    })
       .modulate({ saturation: 0.5 })
-      .toFile(actual)
-      .then(function () {
-        fixtures.assertMaxColourDistance(actual, expected, 25);
-      });
+      .raw()
+      .toBuffer();
+
+    assert.deepStrictEqual({ r: 127, g: 83, b: 81 }, { r, g, b });
   });
 
-  it('should be able to modulate all channels', function () {
-    const base = 'modulate-all.jpg';
-    const actual = fixtures.path('output.' + base);
-    const expected = fixtures.expected(base);
-
-    return sharp(fixtures.inputJpg)
+  it('should be able to modulate all channels', async () => {
+    const [r, g, b] = await sharp({
+      create: {
+        width: 1,
+        height: 1,
+        channels: 3,
+        background: { r: 153, g: 68, b: 68 }
+      }
+    })
       .modulate({ brightness: 2, saturation: 0.5, hue: 180 })
-      .toFile(actual)
-      .then(function () {
-        fixtures.assertMaxColourDistance(actual, expected, 25);
-      });
+      .raw()
+      .toBuffer();
+
+    assert.deepStrictEqual({ r: 149, g: 209, b: 214 }, { r, g, b });
   });
 
-  describe('hue-rotate', function (done) {
-    [30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330, 360].forEach(function (angle) {
-      it('should properly hue rotate by ' + angle + 'deg', function () {
-        const base = 'modulate-hue-angle-' + angle + '.png';
-        const actual = fixtures.path('output.' + base);
+  it('should be able to use linear and modulate together', async () => {
+    const contrast = 1.5;
+    const brightness = 0.5;
+
+    const [r, g, b] = await sharp({
+      create: {
+        width: 1,
+        height: 1,
+        channels: 3,
+        background: { r: 153, g: 68, b: 68 }
+      }
+    })
+      .linear(contrast, -(128 * contrast) + 128)
+      .modulate({ brightness })
+      .raw()
+      .toBuffer();
+
+    assert.deepStrictEqual({ r: 81, g: 0, b: 0 }, { r, g, b });
+  });
+
+  describe('hue-rotate', () => {
+    [30, 60, 90, 120, 150, 180, 210, 240, 270, 300, 330, 360].forEach(angle => {
+      it(`should hue rotate by ${angle} deg`, async () => {
+        const base = `modulate-hue-angle-${angle}.png`;
+        const actual = fixtures.path(`output.${base}`);
         const expected = fixtures.expected(base);
 
-        return sharp(fixtures.testPattern)
+        await sharp(fixtures.testPattern)
+          .resize(320)
           .modulate({ hue: angle })
+          .png({ compressionLevel: 0 })
           .toFile(actual)
-          .then(function () {
-            fixtures.assertMaxColourDistance(actual, expected, 25);
+          .then(() => {
+            fixtures.assertMaxColourDistance(actual, expected);
           });
       });
     });
   });
-
-  it('should be able to use linear and modulate together', function () {
-    const base = 'modulate-linear.jpg';
-    const actual = fixtures.path('output.' + base);
-    const expected = fixtures.expected(base);
-
-    const contrast = 1.5;
-    const brightness = 0.5;
-
-    return sharp(fixtures.testPattern)
-      .linear(contrast, -(128 * contrast) + 128)
-      .modulate({ brightness })
-      .toFile(actual)
-      .then(function () {
-        fixtures.assertMaxColourDistance(actual, expected);
-      });
-  });
 });