diff --git a/NGitLab/Models/Position.cs b/NGitLab/Models/Position.cs
index ed90a38f..c5e99066 100644
--- a/NGitLab/Models/Position.cs
+++ b/NGitLab/Models/Position.cs
@@ -23,7 +23,7 @@ public class Position
     public LineRange LineRange { get; set; }
 
     [JsonPropertyName("base_sha")]
-    public Sha1 BaseSha { get; set; }
+    public Sha1? BaseSha { get; set; }
 
     [JsonPropertyName("head_sha")]
     public Sha1 HeadSha { get; set; }
diff --git a/NGitLab/PublicAPI.Unshipped.txt b/NGitLab/PublicAPI.Unshipped.txt
index c0a663c2..4597e6d2 100644
--- a/NGitLab/PublicAPI.Unshipped.txt
+++ b/NGitLab/PublicAPI.Unshipped.txt
@@ -2773,7 +2773,7 @@ NGitLab.Models.PipelineVariable.PipelineVariable() -> void
 NGitLab.Models.PipelineVariable.Value -> string
 NGitLab.Models.PipelineVariable.VariableType -> string
 NGitLab.Models.Position
-NGitLab.Models.Position.BaseSha.get -> NGitLab.Sha1
+NGitLab.Models.Position.BaseSha.get -> NGitLab.Sha1?
 NGitLab.Models.Position.BaseSha.set -> void
 NGitLab.Models.Position.HeadSha.get -> NGitLab.Sha1
 NGitLab.Models.Position.HeadSha.set -> void