diff --git a/src/DiffEngineViewer.Tests/FileScreenTests.WhitespaceOnly.verified.txt b/src/DiffEngineViewer.Tests/FileScreenTests.WhitespaceOnly.verified.txt
new file mode 100644
index 00000000..0f4ad098
--- /dev/null
+++ b/src/DiffEngineViewer.Tests/FileScreenTests.WhitespaceOnly.verified.txt
@@ -0,0 +1,24 @@
++----------------------------------------------------------------------------------------------+
+| Sample.received.txt <> Sample.verified.txt                                              diff |
++----------------------------------------------+-----------------------------------------------+
+| Sample.received.txt                          | Sample.verified.txt                           |
++----------------------------------------------+-----------------------------------------------+
+|      1  the quick                            |      1  the quick                             |
+| ~    2    brown fox                          | ~    2  brown fox                             |
+| ~    3  dog                                  | ~    3  dog                                   |
+|                                              |                                               |
+|                                              |                                               |
+|                                              |                                               |
+|                                              |                                               |
+|                                              |                                               |
+|                                              |                                               |
+|                                              |                                               |
+|                                              |                                               |
+|                                              |                                               |
+|                                              |                                               |
+|                                              |                                               |
+|                                              |                                               |
+|                                              |                                               |
++----------------------------------------------+-----------------------------------------------+
+| [Accept] [Close]                                                              lines 1-3 of 3 |
++----------------------------------------------------------------------------------------------+
\ No newline at end of file
diff --git a/src/DiffEngineViewer.Tests/FileScreenTests.cs b/src/DiffEngineViewer.Tests/FileScreenTests.cs
index 05b6122a..ce53bbef 100644
--- a/src/DiffEngineViewer.Tests/FileScreenTests.cs
+++ b/src/DiffEngineViewer.Tests/FileScreenTests.cs
@@ -16,6 +16,18 @@ public Task LeftEmpty() =>
     public Task RightEmpty() =>
         Verify(Fixtures.Render(Fixtures.File(right: "")));
 
+    /// <summary>
+    /// A snapshot that differs only in whitespace still has to render as a difference. DiffPlex
+    /// ignores whitespace by default, which turned this into three Unchanged rows.
+    /// </summary>
+    [Test]
+    public Task WhitespaceOnly() =>
+        Verify(
+            Fixtures.Render(
+                Fixtures.File(
+                    "the quick\n  brown fox\ndog ",
+                    "the quick\nbrown fox\ndog")));
+
     [Test]
     public Task LongLines()
     {
diff --git a/src/DiffEngineViewer/DiffRows.cs b/src/DiffEngineViewer/DiffRows.cs
index 635f13aa..708ae671 100644
--- a/src/DiffEngineViewer/DiffRows.cs
+++ b/src/DiffEngineViewer/DiffRows.cs
@@ -10,7 +10,15 @@ static class DiffRows
     public static (IReadOnlyList<Row> Left, IReadOnlyList<Row> Right) Build(string leftText, string rightText)
     {
         // DiffPlex is old/new oriented. Left is the received (new) side, right the expected (old).
-        var model = SideBySideDiffBuilder.Diff(rightText, leftText);
+        // ignoreWhiteSpace defaults to true, which is wrong for a snapshot: a test that fails only
+        // on indentation or a trailing space came back Unchanged on every row, so the panes drew no
+        // markers, NextChange found nothing, and the reviewer was shown a failure with no visible
+        // difference. Whitespace is exactly what the F# layout convention is about.
+        var model = SideBySideDiffBuilder.Diff(
+            rightText,
+            leftText,
+            ignoreWhiteSpace: false,
+            ignoreCase: false);
         return (Convert(model.NewText.Lines), Convert(model.OldText.Lines));
     }