diff --git a/tests/ImageSharp.Tests/Formats/Png/PngDecoderTests.cs b/tests/ImageSharp.Tests/Formats/Png/PngDecoderTests.cs
index 8162d61bd2..53f71fb7b9 100644
--- a/tests/ImageSharp.Tests/Formats/Png/PngDecoderTests.cs
+++ b/tests/ImageSharp.Tests/Formats/Png/PngDecoderTests.cs
@@ -79,6 +79,7 @@ namespace SixLabors.ImageSharp.Tests
             TestImages.Png.VimImage2,
 
             TestImages.Png.Rgb24BppTrans,
+            TestImages.Png.GrayAlpha8Bit
         };
 
         public static readonly string[] TestImages48Bpp =
@@ -101,21 +102,23 @@ namespace SixLabors.ImageSharp.Tests
         public static readonly string[] TestImagesGrayAlpha16Bit =
         {
             TestImages.Png.GrayAlpha16Bit,
-            TestImages.Png.GrayTrns16Bit
+            TestImages.Png.GrayTrns16BitInterlaced
         };
 
         // This is a workaround for Mono-s decoder being incompatible with ours and GDI+.
         // We shouldn't mix these with the Interleaved cases (which are also failing with Mono System.Drawing). Let's go AAA!
         private static readonly string[] SkipOnMono =
-            {
-                TestImages.Png.Bad.ChunkLength2,
-                TestImages.Png.VimImage2,
-                TestImages.Png.Splash,
-                TestImages.Png.Indexed,
-                TestImages.Png.Bad.ChunkLength1,
-                TestImages.Png.VersioningImage1,
-                TestImages.Png.Banner7Adam7InterlaceMode,
-            };
+        {
+            TestImages.Png.Bad.ChunkLength2,
+            TestImages.Png.VimImage2,
+            TestImages.Png.Splash,
+            TestImages.Png.Indexed,
+            TestImages.Png.Bad.ChunkLength1,
+            TestImages.Png.VersioningImage1,
+            TestImages.Png.Banner7Adam7InterlaceMode,
+            TestImages.Png.GrayTrns16BitInterlaced,
+            TestImages.Png.Rgb48BppInterlaced
+        };
 
         private static bool SkipVerification(ITestImageProvider provider)
         {
diff --git a/tests/ImageSharp.Tests/PixelFormats/Rgb48Tests.cs b/tests/ImageSharp.Tests/PixelFormats/Rgb48Tests.cs
index ae8cb968af..77d6544f00 100644
--- a/tests/ImageSharp.Tests/PixelFormats/Rgb48Tests.cs
+++ b/tests/ImageSharp.Tests/PixelFormats/Rgb48Tests.cs
@@ -103,6 +103,21 @@ namespace SixLabors.ImageSharp.Tests.PixelFormats
             Assert.Equal(expected, actual);
         }
 
+        [Fact]
+        public void Rgb48_ToArgb32()
+        {
+            // arrange
+            var rgba48 = new Rgb48(0.08f, 0.15f, 0.30f);
+            var actual = default(Argb32);
+            var expected = new Argb32(20, 38, 76, 255);
+
+            // act
+            rgba48.ToArgb32(ref actual);
+
+            // assert
+            Assert.Equal(expected, actual);
+        }
+
         [Fact]
         public void Rgba64_ToBgr24()
         {
diff --git a/tests/ImageSharp.Tests/PixelFormats/Rgba64Tests.cs b/tests/ImageSharp.Tests/PixelFormats/Rgba64Tests.cs
index 12f4d7afc5..92b36a1c62 100644
--- a/tests/ImageSharp.Tests/PixelFormats/Rgba64Tests.cs
+++ b/tests/ImageSharp.Tests/PixelFormats/Rgba64Tests.cs
@@ -105,6 +105,21 @@ namespace SixLabors.ImageSharp.Tests.PixelFormats
             Assert.Equal(expected, actual);
         }
 
+        [Fact]
+        public void Rgba64_ToArgb32()
+        {
+            // arrange
+            var rgba64 = new Rgba64(0.08f, 0.15f, 0.30f, 0.45f);
+            var actual = default(Argb32);
+            var expected = new Argb32(20, 38, 76, 115);
+
+            // act
+            rgba64.ToArgb32(ref actual);
+
+            // assert
+            Assert.Equal(expected, actual);
+        }
+
         [Fact]
         public void Rgba64_ToBgr24()
         {
@@ -155,7 +170,7 @@ namespace SixLabors.ImageSharp.Tests.PixelFormats
         public void Rgb48_PackFromRgb48_ToRgb48()
         {
             // arrange
-            var input = default(Rgb48);
+            var input = default(Rgba64);
             var actual = default(Rgb48);
             var expected = new Rgb48(65535, 0, 65535);
 
diff --git a/tests/ImageSharp.Tests/TestImages.cs b/tests/ImageSharp.Tests/TestImages.cs
index 8722c8b48a..6d3a76e75f 100644
--- a/tests/ImageSharp.Tests/TestImages.cs
+++ b/tests/ImageSharp.Tests/TestImages.cs
@@ -28,8 +28,9 @@ namespace SixLabors.ImageSharp.Tests
             public const string Bpp1 = "Png/bpp1.png";
             public const string Gray4Bpp = "Png/gray_4bpp.png";
             public const string Gray16Bit = "Png/gray-16.png";
+            public const string GrayAlpha8Bit = "Png/gray-alpha-8.png";
             public const string GrayAlpha16Bit = "Png/gray-alpha-16.png";
-            public const string GrayTrns16Bit = "Png/gray-16-tRNS.png";
+            public const string GrayTrns16BitInterlaced = "Png/gray-16-tRNS-interlaced.png";
             public const string Rgb24BppTrans = "Png/rgb-8-tRNS.png";
             public const string Rgb48Bpp = "Png/rgb-48bpp.png";
             public const string Rgb48BppInterlaced = "Png/rgb-48bpp-interlaced.png";
diff --git a/tests/Images/External b/tests/Images/External
index 94cc43a65e..6fcee2ccd5 160000
--- a/tests/Images/External
+++ b/tests/Images/External
@@ -1 +1 @@
-Subproject commit 94cc43a65e304aa312bea9d098206086095e6dff
+Subproject commit 6fcee2ccd5e8bac98a0290b467ad86bb02d00b6c
diff --git a/tests/Images/Input/Png/gray-16-tRNS.png b/tests/Images/Input/Png/gray-16-tRNS-interlaced.png
similarity index 100%
rename from tests/Images/Input/Png/gray-16-tRNS.png
rename to tests/Images/Input/Png/gray-16-tRNS-interlaced.png
diff --git a/tests/Images/Input/Png/gray-alpha-8.png b/tests/Images/Input/Png/gray-alpha-8.png
new file mode 100644
index 0000000000..eb0a924998
Binary files /dev/null and b/tests/Images/Input/Png/gray-alpha-8.png differ