diff --git a/src/libraries/System.Runtime.InteropServices.JavaScript/src/System/Runtime/InteropServices/JavaScript/Marshaling/JSMarshalerArgument.DateTime.cs b/src/libraries/System.Runtime.InteropServices.JavaScript/src/System/Runtime/InteropServices/JavaScript/Marshaling/JSMarshalerArgument.DateTime.cs
index 575139fa8cf07f..8b1674eecd789e 100644
--- a/src/libraries/System.Runtime.InteropServices.JavaScript/src/System/Runtime/InteropServices/JavaScript/Marshaling/JSMarshalerArgument.DateTime.cs
+++ b/src/libraries/System.Runtime.InteropServices.JavaScript/src/System/Runtime/InteropServices/JavaScript/Marshaling/JSMarshalerArgument.DateTime.cs
@@ -107,7 +107,7 @@ public void ToManaged(out DateTime value)
         public void ToJS(DateTime value)
         {
             slot.Type = MarshalerType.DateTime;
-            slot.DoubleValue = new DateTimeOffset(value).ToUnixTimeMilliseconds();
+            slot.DoubleValue = new DateTimeOffset(value.Ticks, TimeSpan.Zero).ToUnixTimeMilliseconds();
         }
 
         /// <summary>
@@ -141,7 +141,7 @@ public void ToJS(DateTime? value)
             if (value.HasValue)
             {
                 slot.Type = MarshalerType.DateTime;
-                slot.DoubleValue = new DateTimeOffset(value.Value).ToUnixTimeMilliseconds();
+                slot.DoubleValue = new DateTimeOffset(value.Value.Ticks, TimeSpan.Zero).ToUnixTimeMilliseconds();
             }
             else
             {
diff --git a/src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System.Runtime.InteropServices.JavaScript.Tests.csproj b/src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System.Runtime.InteropServices.JavaScript.Tests.csproj
index 7da762fed4180d..15e2c682f6ecab 100644
--- a/src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System.Runtime.InteropServices.JavaScript.Tests.csproj
+++ b/src/libraries/System.Runtime.InteropServices.JavaScript/tests/System.Runtime.InteropServices.JavaScript.UnitTests/System.Runtime.InteropServices.JavaScript.Tests.csproj
@@ -7,6 +7,7 @@
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <TestRuntime>true</TestRuntime>
     <WasmXHarnessArgs>$(WasmXHarnessArgs) --engine-arg=--expose-gc --web-server-use-cop</WasmXHarnessArgs>
+    <WasmXHarnessMonoArgs>$(WasmXHarnessMonoArgs) --setenv=TZ=Europe/Berlin</WasmXHarnessMonoArgs>
     <EnableAggressiveTrimming>true</EnableAggressiveTrimming>
     <PublishTrimmed>true</PublishTrimmed>
     <DefineConstants Condition="'$(WasmEnableThreads)' == 'true'">$(DefineConstants);FEATURE_WASM_MANAGED_THREADS</DefineConstants>