diff --git a/src/FSharp.Data.Runtime.Utilities/Pluralizer.fs b/src/FSharp.Data.Runtime.Utilities/Pluralizer.fs
index ebd505a18..4ca702bbc 100644
--- a/src/FSharp.Data.Runtime.Utilities/Pluralizer.fs
+++ b/src/FSharp.Data.Runtime.Utilities/Pluralizer.fs
@@ -50,6 +50,7 @@ let private tables =
 
                "cis", "ces"
                "us", "uses"
+               "ase", "ases"
                "sis", "ses"
                "xis", "xes"
 
@@ -148,6 +149,7 @@ let private tables =
                "murex", "murecis", ""
                "mythos", "mythos", "mythoi"
                "news", "", ""
+               "oasis", "oases", ""
                "octopus", "octopuses", "octopodes"
                "ovum", "ova", ""
                "ox", "ox", "oxen"
diff --git a/tests/FSharp.Data.Core.Tests/Pluralizer.fs b/tests/FSharp.Data.Core.Tests/Pluralizer.fs
index cbe07d2d2..b266bc58e 100644
--- a/tests/FSharp.Data.Core.Tests/Pluralizer.fs
+++ b/tests/FSharp.Data.Core.Tests/Pluralizer.fs
@@ -202,6 +202,21 @@ let ``Roundtrip consistency for common words`` () =
            word <> "aircraft" && word <> "series" then
             backToSingular |> should equal word
 
+[<Test>]
+let ``Purchases singularizes correctly - regression test for issue 1508`` () =
+    // Previously "purchases" was incorrectly singularized to "purchasis"
+    // due to the "sis"/"ses" suffix rule matching words ending in "ses"
+    toSingular "purchases" |> should equal "purchase"
+    toPlural "purchase" |> should equal "purchases"
+    // Other "-ase" words should also work correctly
+    toSingular "cases" |> should equal "case"
+    toSingular "phases" |> should equal "phase"
+    toSingular "phrases" |> should equal "phrase"
+    toSingular "vases" |> should equal "vase"
+    // "oases" should still correctly singularize to "oasis" (via special word list)
+    toSingular "oases" |> should equal "oasis"
+    toPlural "oasis" |> should equal "oases"
+
 [<Test>]
 let ``Performance with repeated calls`` () =
     // Test that repeated calls with same input work correctly (testing lazy initialization)