diff --git a/tests/AVEVA.Historian.Client.Tests/HistorianTagWriteProtocolTests.cs b/tests/AVEVA.Historian.Client.Tests/HistorianTagWriteProtocolTests.cs
index bee045f..dba3736 100644
--- a/tests/AVEVA.Historian.Client.Tests/HistorianTagWriteProtocolTests.cs
+++ b/tests/AVEVA.Historian.Client.Tests/HistorianTagWriteProtocolTests.cs
@@ -62,6 +62,28 @@ public sealed class HistorianTagWriteProtocolTests
         + "09120052657465737453646B5772697465496E7432"
         + "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
         + "09180053444B2077726974652D52452073616E64626F78207461670904004D44415302010100000001E8030000549B0E36EDDBDC011A030904007465737410270000000000000000F03FFE00")]
+    // UInt1/Int8/UInt8 (H1 un-gate): prefix is the captured Double buffer; only the data-type code byte differs.
+    [InlineData(
+        AVEVA.Historian.Client.Models.HistorianDataType.Int8,
+        "RetestSdkWriteDouble", 0x01dcdbed24988f3aL,
+        "4E6703000100000004C6021900000000000000000000000000000000"
+        + "09140052657465737453646B5772697465446F75626C65"
+        + "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+        + "09180053444B2077726974652D52452073616E64626F78207461670904004D44415302010100000001E80300003A8F9824EDDBDC011A030904007465737410270000000000000000F03FFE00")]
+    [InlineData(
+        AVEVA.Historian.Client.Models.HistorianDataType.UInt8,
+        "RetestSdkWriteDouble", 0x01dcdbed24988f3aL,
+        "4E6703000100000004C6023900000000000000000000000000000000"
+        + "09140052657465737453646B5772697465446F75626C65"
+        + "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+        + "09180053444B2077726974652D52452073616E64626F78207461670904004D44415302010100000001E80300003A8F9824EDDBDC011A030904007465737410270000000000000000F03FFE00")]
+    [InlineData(
+        AVEVA.Historian.Client.Models.HistorianDataType.UInt1,
+        "RetestSdkWriteDouble", 0x01dcdbed24988f3aL,
+        "4E6703000100000004C6020800000000000000000000000000000000"
+        + "09140052657465737453646B5772697465446F75626C65"
+        + "FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF"
+        + "09180053444B2077726974652D52452073616E64626F78207461670904004D44415302010100000001E80300003A8F9824EDDBDC011A030904007465737410270000000000000000F03FFE00")]
     public void SerializeAnalogCTagMetadata_PerDataType_MatchesCapturedNativeBytes(
         AVEVA.Historian.Client.Models.HistorianDataType dataType,
         string tagName,
diff --git a/tests/AVEVA.Historian.Client.Tests/WcfHistoricalWriteProtocolTests.cs b/tests/AVEVA.Historian.Client.Tests/WcfHistoricalWriteProtocolTests.cs
index 3e142d5..98b902c 100644
--- a/tests/AVEVA.Historian.Client.Tests/WcfHistoricalWriteProtocolTests.cs
+++ b/tests/AVEVA.Historian.Client.Tests/WcfHistoricalWriteProtocolTests.cs
@@ -21,6 +21,13 @@ public sealed class WcfHistoricalWriteProtocolTests
         "4f4e0100380000002e00" + "ca9735f7f841b244b56f9c14ccfeac32" + "b09bc72fd701dd01" + "c000" + "c0100100" + "104b59f3e701dd01" + "0000000039300000")]
     [InlineData(HistorianDataType.UInt4, 305419896d,
         "4f4e0100380000002e00" + "e7ae22d8e4cc65439ebd8bcb09402974" + "602d6663d701dd01" + "c000" + "c0100100" + "498af726e801dd01" + "0000000078563412")]
+    // UInt1/Int8/UInt8 (H1 un-gate): prefix is the captured Double buffer; only the data-type code / value bytes differ. Live round-trip confirms (gateway HistorianTypeRoundTripTests).
+    [InlineData(HistorianDataType.Int8, 100000d,
+        "4f4e01003c0000003200" + "7f970bb0b5a7344bb7bf6899ff06d027" + "c07d5f23d701dd01" + "c000" + "c0100100" + "08eff1e6e701dd01" + "00000000a086010000000000")]
+    [InlineData(HistorianDataType.UInt8, 100001d,
+        "4f4e01003c0000003200" + "7f970bb0b5a7344bb7bf6899ff06d027" + "c07d5f23d701dd01" + "c000" + "c0100100" + "08eff1e6e701dd01" + "00000000a186010000000000")]
+    [InlineData(HistorianDataType.UInt1, 7d,
+        "4f4e0100" + "35000000" + "2b00" + "7f970bb0b5a7344bb7bf6899ff06d027" + "c07d5f23d701dd01" + "c000" + "c0100100" + "08eff1e6e701dd01" + "00000000" + "07")]
     public void SerializeAddStreamValuesBuffer_MatchesCapturedNativeBuffer(HistorianDataType dataType, double value, string capturedHex)
     {
         byte[] captured = Convert.FromHexString(capturedHex);