diff --git a/src/ImageProcessor/Formats/Png/PngDecoderCore.cs b/src/ImageProcessor/Formats/Png/PngDecoderCore.cs
index 2ae91f258..85ed12c12 100644
--- a/src/ImageProcessor/Formats/Png/PngDecoderCore.cs
+++ b/src/ImageProcessor/Formats/Png/PngDecoderCore.cs
@@ -201,6 +201,7 @@ namespace ImageProcessor.Formats
             Array.Reverse(data, 0, 4);
             Array.Reverse(data, 4, 4);
 
+            // 39.3700787 = inches in a meter.
             this.currentImage.HorizontalResolution = BitConverter.ToInt32(data, 0) / 39.3700787d;
             this.currentImage.VerticalResolution = BitConverter.ToInt32(data, 4) / 39.3700787d;
         }
diff --git a/tests/ImageProcessor.Tests/TestImages/Formats/Png/mountain.png.REMOVED.git-id b/tests/ImageProcessor.Tests/TestImages/Formats/Png/mountain.png.REMOVED.git-id
new file mode 100644
index 000000000..e10578b3c
--- /dev/null
+++ b/tests/ImageProcessor.Tests/TestImages/Formats/Png/mountain.png.REMOVED.git-id
@@ -0,0 +1 @@
+e51bffc5ceb300a70039c9c3ce4542eff47925ea
\ No newline at end of file