diff --git a/SlackNet.Tests/UtilsTests.cs b/SlackNet.Tests/UtilsTests.cs
index 87fe0d1..076893e 100644
--- a/SlackNet.Tests/UtilsTests.cs
+++ b/SlackNet.Tests/UtilsTests.cs
@@ -34,6 +34,7 @@ public void ToDateTime_FromTimestampString_InvalidTimestamp_ReturnsNull()
     public void ToDateTime_FromTimestampString_ValidTimestamp_ReturnsDateTime()
     {
         "42".ToDateTime().ShouldBe(new DateTime(1970, 1, 1, 0, 0, 42));
+        "42.123456".ToDateTime().ShouldBe(new DateTime(1970, 1, 1, 0, 0, 42, 123, 456));
         "-42".ToDateTime().ShouldBe(new DateTime(1969, 12, 31, 23, 59, 18));
     }
 
@@ -60,6 +61,7 @@ public void ToDateTime_FromDecimal_Zero_ReturnsNull()
     public void ToDateTime_FromDecimal_NonZero_ReturnsDateTime()
     {
         42m.ToDateTime().ShouldBe(new DateTime(1970, 1, 1, 0, 0, 42));
+        42.123456m.ToDateTime().ShouldBe(new DateTime(1970, 1, 1, 0, 0, 42, 123, 456));
         (-42m).ToDateTime().ShouldBe(new DateTime(1969, 12, 31, 23, 59, 18));
     }
 
diff --git a/SlackNet/Utils.cs b/SlackNet/Utils.cs
index 9226de2..10a3c7f 100644
--- a/SlackNet/Utils.cs
+++ b/SlackNet/Utils.cs
@@ -34,7 +34,9 @@ public static class Utils
     /// <returns>If timestamp is 0, returns null, otherwise a DateTime.</returns>
     public static DateTime? ToDateTime(this decimal timestamp) =>
         timestamp != 0
-            ? DateTimeOffset.FromUnixTimeMilliseconds((long)(timestamp * 1000)).UtcDateTime
+            ? DateTimeOffset.FromUnixTimeMilliseconds((long)(timestamp * 1000))
+                .AddTicks((long)(timestamp * 1_000_000 % 1000 * 10)) // 10 ticks per microsecond
+                .UtcDateTime
             : null;
 
     /// <summary>