diff --git a/src/Testcontainers/Clients/TestcontainersClient.cs b/src/Testcontainers/Clients/TestcontainersClient.cs
index d7b397c1b..4d54139cb 100644
--- a/src/Testcontainers/Clients/TestcontainersClient.cs
+++ b/src/Testcontainers/Clients/TestcontainersClient.cs
@@ -98,10 +98,10 @@ public Task<long> GetContainerExitCodeAsync(string id, CancellationToken ct = de
     /// <inheritdoc />
     public Task<(string Stdout, string Stderr)> GetContainerLogsAsync(string id, DateTime since = default, DateTime until = default, bool timestampsEnabled = true, CancellationToken ct = default)
     {
-#if NETSTANDARD2_1_OR_GREATER
-      var unixEpoch = DateTime.UnixEpoch;
-#else
+#if NETSTANDARD2_0
       var unixEpoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+#else
+      var unixEpoch = DateTime.UnixEpoch;
 #endif
 
       if (default(DateTime).Equals(since))
@@ -269,11 +269,11 @@ public async Task<byte[]> ReadFileAsync(string id, string filePath, Cancellation
 
         var readBytes = new byte[entry.Size];
 
-#if NETSTANDARD2_1_OR_GREATER
-        _ = await tarInputStream.ReadAsync(new Memory<byte>(readBytes), ct)
+#if NETSTANDARD2_0
+        _ = await tarInputStream.ReadAsync(readBytes, 0, readBytes.Length, ct)
           .ConfigureAwait(false);
 #else
-        _ = await tarInputStream.ReadAsync(readBytes, 0, readBytes.Length, ct)
+        _ = await tarInputStream.ReadAsync(readBytes, ct)
           .ConfigureAwait(false);
 #endif
 
diff --git a/src/Testcontainers/Containers/ResourceReaper.cs b/src/Testcontainers/Containers/ResourceReaper.cs
index 617ee0c37..f941f2f92 100644
--- a/src/Testcontainers/Containers/ResourceReaper.cs
+++ b/src/Testcontainers/Containers/ResourceReaper.cs
@@ -306,11 +306,11 @@ await tcpClient.ConnectAsync(host, port)
             {
               using (var messageBuffer = new MemoryStream())
               {
-#if NETSTANDARD2_1_OR_GREATER
-                await stream.WriteAsync(new ReadOnlyMemory<byte>(sendBytes), ct)
+#if NETSTANDARD2_0
+                await stream.WriteAsync(sendBytes, 0, sendBytes.Length, ct)
                   .ConfigureAwait(false);
 #else
-                await stream.WriteAsync(sendBytes, 0, sendBytes.Length, ct)
+                await stream.WriteAsync(sendBytes, ct)
                   .ConfigureAwait(false);
 #endif
 
@@ -321,11 +321,11 @@ await stream.FlushAsync(ct)
 
                 do
                 {
-#if NETSTANDARD2_1_OR_GREATER
-                  var numberOfBytes = await stream.ReadAsync(new Memory<byte>(readBytes), ct)
+#if NETSTANDARD2_0
+                  var numberOfBytes = await stream.ReadAsync(readBytes, 0, readBytes.Length, ct)
                     .ConfigureAwait(false);
 #else
-                  var numberOfBytes = await stream.ReadAsync(readBytes, 0, readBytes.Length, ct)
+                  var numberOfBytes = await stream.ReadAsync(readBytes, ct)
                     .ConfigureAwait(false);
 #endif
 
@@ -367,11 +367,11 @@ await Task.Delay(TimeSpan.FromSeconds(RetryTimeoutInSeconds), ct)
             while (!_maintainConnectionCts.IsCancellationRequested)
             {
               // Keep the connection to Ryuk up.
-#if NETSTANDARD2_1_OR_GREATER
-              _ = await stream.ReadAsync(new Memory<byte>(readBytes), _maintainConnectionCts.Token)
+#if NETSTANDARD2_0
+              _ = await stream.ReadAsync(readBytes, 0, readBytes.Length, _maintainConnectionCts.Token)
                 .ConfigureAwait(false);
 #else
-              _ = await stream.ReadAsync(readBytes, 0, readBytes.Length, _maintainConnectionCts.Token)
+              _ = await stream.ReadAsync(readBytes, _maintainConnectionCts.Token)
                 .ConfigureAwait(false);
 #endif
             }
diff --git a/src/Testcontainers/Containers/TarOutputMemoryStream.cs b/src/Testcontainers/Containers/TarOutputMemoryStream.cs
index 245362f98..99ae0d99c 100644
--- a/src/Testcontainers/Containers/TarOutputMemoryStream.cs
+++ b/src/Testcontainers/Containers/TarOutputMemoryStream.cs
@@ -74,11 +74,11 @@ public async Task AddAsync(IResourceMapping resourceMapping, CancellationToken c
       await PutNextEntryAsync(tarEntry, ct)
         .ConfigureAwait(false);
 
-#if NETSTANDARD2_1_OR_GREATER
-      await WriteAsync(fileContent, ct)
+#if NETSTANDARD2_0
+      await WriteAsync(fileContent, 0, fileContent.Length, ct)
         .ConfigureAwait(false);
 #else
-      await WriteAsync(fileContent, 0, fileContent.Length, ct)
+      await WriteAsync(fileContent, ct)
         .ConfigureAwait(false);
 #endif
 
diff --git a/src/Testcontainers/Images/IgnoreFile.cs b/src/Testcontainers/Images/IgnoreFile.cs
index 7698787be..d5d3ec336 100644
--- a/src/Testcontainers/Images/IgnoreFile.cs
+++ b/src/Testcontainers/Images/IgnoreFile.cs
@@ -193,10 +193,10 @@ public string Replace(string input)
         }
 
         // Replace the last non recursive wildcard with a match-zero-or-one quantifier regular expression.
-#if NETSTANDARD2_1_OR_GREATER
-        if (input.Contains('*') && index >= 0)
-#else
+#if NETSTANDARD2_0
         if (input.Contains("*") && index >= 0)
+#else
+        if (input.Contains('*') && index >= 0)
 #endif
         {
           input = input.Remove(index, 1).Insert(index, $"{MatchAllExceptPathSeparator}?");