diff --git a/src/libraries/System.Memory/tests/System.Memory.Tests.csproj b/src/libraries/System.Memory/tests/System.Memory.Tests.csproj
index 2de051c81fbdba..caeabbd3565c07 100644
--- a/src/libraries/System.Memory/tests/System.Memory.Tests.csproj
+++ b/src/libraries/System.Memory/tests/System.Memory.Tests.csproj
@@ -4,6 +4,7 @@
     <TestRuntime>true</TestRuntime>
     <IncludeRemoteExecutor>true</IncludeRemoteExecutor>
     <TargetFramework>$(NetCoreAppCurrent)</TargetFramework>
+    <XunitShowProgress>true</XunitShowProgress>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/libraries/System.Private.CoreLib/src/System/Buffers/Text/Base64Helper/Base64ValidatorHelper.cs b/src/libraries/System.Private.CoreLib/src/System/Buffers/Text/Base64Helper/Base64ValidatorHelper.cs
index 6ab37cfc49436f..c26e5b274da1d4 100644
--- a/src/libraries/System.Private.CoreLib/src/System/Buffers/Text/Base64Helper/Base64ValidatorHelper.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Buffers/Text/Base64Helper/Base64ValidatorHelper.cs
@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
 
 namespace System.Buffers.Text
 {
@@ -11,6 +12,8 @@ internal static bool IsValid<T, TBase64Validatable>(TBase64Validatable validatab
             where TBase64Validatable : IBase64Validatable<T>
             where T : struct
         {
+            if (!base64Text.IsEmpty && Unsafe.IsNullRef(ref MemoryMarshal.GetReference(base64Text))) throw new InvalidOperationException("Base64Helper1: Span is empty or not initialized properly. " + base64Text.Length);
+
             int length = 0, paddingCount = 0;
             T lastChar = default;
 
@@ -139,9 +142,16 @@ internal interface IBase64Validatable<T>
             bool IsEncodingPad(T value);
             bool ValidateAndDecodeLength(T lastChar, int length, int paddingCount, out int decodedLength);
         }
-
+#pragma warning disable CS0414
         internal readonly struct Base64CharValidatable : IBase64Validatable<char>
         {
+            // to make structure size 4 instead of 1 as workaround for WASM AOT problem with empty structs
+            private readonly int dummy;
+            public Base64CharValidatable()
+            {
+                dummy = 0;
+            }
+
 #if NET
             private static readonly SearchValues<char> s_validBase64Chars = SearchValues.Create("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/");
 
@@ -167,6 +177,13 @@ public bool ValidateAndDecodeLength(char lastChar, int length, int paddingCount,
 
         internal readonly struct Base64ByteValidatable : IBase64Validatable<byte>
         {
+            // to make structure size 4 instead of 1 as workaround for WASM AOT problem with empty structs
+            private readonly int dummy;
+            public Base64ByteValidatable()
+            {
+                dummy = 0;
+            }
+
 #if NET
             private static readonly SearchValues<byte> s_validBase64Chars = SearchValues.Create(default(Base64EncoderByte).EncodingMap);