diff --git a/src/ServiceToolkit/src/SIL.ServiceToolkit/Services/ParallelCorpusPreprocessingService.cs b/src/ServiceToolkit/src/SIL.ServiceToolkit/Services/ParallelCorpusPreprocessingService.cs
index 7ef4d67c..40b06ccb 100644
--- a/src/ServiceToolkit/src/SIL.ServiceToolkit/Services/ParallelCorpusPreprocessingService.cs
+++ b/src/ServiceToolkit/src/SIL.ServiceToolkit/Services/ParallelCorpusPreprocessingService.cs
@@ -102,7 +102,9 @@ public async Task Preprocess(
                         .ChooseRandom(Seed)
                         .AlignRows(targetTermCorpora.ChooseFirst());
                     foreach (
-                        ParallelTextRow row in parallelKeyTermsCorpus.DistinctBy(row => row.SourceText + row.TargetText)
+                        ParallelTextRow row in parallelKeyTermsCorpus.DistinctBy(row =>
+                            (row.SourceText, row.TargetText)
+                        )
                     )
                     {
                         await train(new Row(row.TextId, row.Refs, row.SourceText, row.TargetText, 1));