diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs b/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs
index 2edbadda..92669fc3 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OtOpcUaNodeManager.cs
@@ -1902,7 +1902,9 @@ public sealed class OtOpcUaNodeManager : CustomNodeManager2
                 // The over-fetch cap MUST be explicit and non-zero: a cap of 0 falls back to the backend's
                 // MaxValuesPerRead, which would re-introduce the very stall we're escaping. +1 over the bound
                 // lets us DETECT a cluster strictly larger than the bound (the absurd-burst backstop below).
-                var overfetchCap = (uint)(MaxTieClusterOverfetch + 1);
+                // Compute in uint so +1 can never wrap: Math.Max(1,…) also guards against a zero/negative
+                // config value slipping through (Validate() warns but does not block startup).
+                var overfetchCap = (uint)Math.Max(1, MaxTieClusterOverfetch) + 1u;
                 var cluster = HistorianDataSource
                     .ReadRawAsync(tagname, startUtc, startUtc, overfetchCap, CancellationToken.None)
                     .GetAwaiter().GetResult().Samples;
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Historian/ServerHistorianOptions.cs b/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Historian/ServerHistorianOptions.cs
index 96908f43..572ce05e 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Historian/ServerHistorianOptions.cs
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Historian/ServerHistorianOptions.cs
@@ -63,6 +63,9 @@ public sealed class ServerHistorianOptions
             warnings.Add("ServerHistorian:SharedSecret is empty while the historian is enabled — the Wonderware sidecar Hello frame will carry an empty secret.");
         if (Port <= 0)
             warnings.Add($"ServerHistorian:Port is {Port} — must be > 0; the read client cannot dial the sidecar.");
+        // MaxTieClusterOverfetch is intentionally checked AFTER the Enabled early-return above:
+        // the over-fetch code path only runs when a real IHistorianDataSource is wired in,
+        // so a zero/negative value is harmless (and noise-free) when the historian is disabled.
         if (MaxTieClusterOverfetch <= 0)
             warnings.Add($"ServerHistorian:MaxTieClusterOverfetch is {MaxTieClusterOverfetch} — must be > 0; HistoryRead-Raw cannot page within an oversized tie cluster and will surface BadHistoryOperationUnsupported for those reads.");
         return warnings;