diff --git a/src/libraries/System.Security.Cryptography/tests/AesTests.Browser.cs b/src/libraries/System.Security.Cryptography/tests/AesTests.Browser.cs
index 5e8eafbaa381ad..6e2d7322f53504 100644
--- a/src/libraries/System.Security.Cryptography/tests/AesTests.Browser.cs
+++ b/src/libraries/System.Security.Cryptography/tests/AesTests.Browser.cs
@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Reflection;
 using Xunit;
 
 namespace System.Security.Cryptography.Tests
@@ -58,5 +59,17 @@ public static void Aes_InvalidKeySize_192_Browser()
                 Assert.Throws<ArgumentException>(() => aes.CreateDecryptor(key192, s_iv));
             }
         }
+
+        [Fact]
+        public static void EnsureSubtleCryptoIsUsed()
+        {
+            bool canUseSubtleCrypto = (bool)Type.GetType("Interop+BrowserCrypto, System.Security.Cryptography")
+                .GetField("CanUseSubtleCrypto", BindingFlags.NonPublic | BindingFlags.Static)
+                .GetValue(null);
+
+            bool expectedCanUseSubtleCrypto = Environment.GetEnvironmentVariable("TEST_EXPECT_SUBTLE_CRYPTO") == "true";
+
+            Assert.Equal(expectedCanUseSubtleCrypto, canUseSubtleCrypto);
+        }
     }
 }
diff --git a/src/libraries/System.Security.Cryptography/tests/System.Security.Cryptography.Tests.csproj b/src/libraries/System.Security.Cryptography/tests/System.Security.Cryptography.Tests.csproj
index 8334efeb1621de..f65e9056134c8c 100644
--- a/src/libraries/System.Security.Cryptography/tests/System.Security.Cryptography.Tests.csproj
+++ b/src/libraries/System.Security.Cryptography/tests/System.Security.Cryptography.Tests.csproj
@@ -9,8 +9,12 @@
   <!-- DesignTimeBuild requires all the TargetFramework Derived Properties to not be present in the first property group. -->
   <PropertyGroup>
     <TargetPlatformIdentifier>$([MSBuild]::GetTargetPlatformIdentifier('$(TargetFramework)'))</TargetPlatformIdentifier>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(TargetOS)' == 'Browser'">
+    <HelixTargetsFile>wasm.helix.targets</HelixTargetsFile>
 
-    <HelixTargetsFile Condition="'$(TargetOS)' == 'Browser'">wasm.helix.targets</HelixTargetsFile>
+    <WasmXHarnessMonoArgs Condition="'$(ContinuousIntegrationBuild)' != 'true' and '$(UseSubtleCryptoForTests)' == 'true'">$(WasmXHarnessMonoArgs) --setenv=TEST_EXPECT_SUBTLE_CRYPTO=true</WasmXHarnessMonoArgs>
+    <WasmXHarnessArgs Condition="'$(ContinuousIntegrationBuild)' != 'true' and '$(UseSubtleCryptoForTests)' == 'true'">$(WasmXHarnessArgs) --web-server-use-cop</WasmXHarnessArgs>
   </PropertyGroup>
   <PropertyGroup Condition="'$(TargetPlatformIdentifier)' == 'Android'">
     <UseAndroidCrypto>true</UseAndroidCrypto>
diff --git a/src/libraries/System.Security.Cryptography/tests/wasm.helix.targets b/src/libraries/System.Security.Cryptography/tests/wasm.helix.targets
index ecb37438b651b1..e14095c075678b 100644
--- a/src/libraries/System.Security.Cryptography/tests/wasm.helix.targets
+++ b/src/libraries/System.Security.Cryptography/tests/wasm.helix.targets
@@ -21,8 +21,8 @@
         <Command>$(HelixCommand)</Command>
         <Timeout>$(_workItemTimeout)</Timeout>
 
-        <PreCommands Condition="'$(OS)' == 'Windows_NT'">set &quot;WasmXHarnessArgs=%WasmXHarnessArgs% --web-server-use-cop&quot;</PreCommands>
-        <PreCommands Condition="'$(OS)' != 'Windows_NT'">export &quot;WasmXHarnessArgs=$WasmXHarnessArgs --web-server-use-cop&quot;</PreCommands>
+        <PreCommands Condition="'$(OS)' == 'Windows_NT'">set &quot;WasmXHarnessArgs=%WasmXHarnessArgs% --web-server-use-cop&quot; &amp; set &quot;WasmXHarnessMonoArgs=--setenv=TEST_EXPECT_SUBTLE_CRYPTO=true&quot;</PreCommands>
+        <PreCommands Condition="'$(OS)' != 'Windows_NT'">export &quot;WasmXHarnessArgs=$WasmXHarnessArgs --web-server-use-cop&quot; &amp;&amp; export &quot;WasmXHarnessMonoArgs=--setenv=TEST_EXPECT_SUBTLE_CRYPTO=true&quot;</PreCommands>
       </HelixWorkItem>
 
       <_CryptoHelixItem Include="@(HelixWorkItem)"