diff --git a/QRCoder/Framework4.0Methods/Stream4Methods.cs b/QRCoder/Extensions/StreamExtensions.cs
similarity index 50%
rename from QRCoder/Framework4.0Methods/Stream4Methods.cs
rename to QRCoder/Extensions/StreamExtensions.cs
index 6c58eb7a..14796167 100644
--- a/QRCoder/Framework4.0Methods/Stream4Methods.cs
+++ b/QRCoder/Extensions/StreamExtensions.cs
@@ -1,13 +1,12 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-
-namespace QRCoder.Framework4._0Methods
+#if NET35
+namespace QRCoder
 {
-    class Stream4Methods
+    internal static class StreamExtensions
     {
-        public static void CopyTo(System.IO.Stream input, System.IO.Stream output)
+        /// <summary>
+        /// Copies a stream to another stream.
+        /// </summary>
+        public static void CopyTo(this System.IO.Stream input, System.IO.Stream output)
         {
             byte[] buffer = new byte[16 * 1024];
             int bytesRead;
@@ -18,3 +17,4 @@ public static void CopyTo(System.IO.Stream input, System.IO.Stream output)
         }
     }
 }
+#endif
diff --git a/QRCoder/Extensions/StringExtensions.cs b/QRCoder/Extensions/StringExtensions.cs
new file mode 100644
index 00000000..34a44272
--- /dev/null
+++ b/QRCoder/Extensions/StringExtensions.cs
@@ -0,0 +1,27 @@
+namespace QRCoder
+{
+    internal static class StringExtensions
+    {
+        /// <summary>
+        /// Indicates whether the specified string is null, empty, or consists only of white-space characters.
+        /// </summary>
+        /// <returns>
+        ///   <see langword="true"/> if the <paramref name="value"/> is null, empty, or white space; otherwise, <see langword="false"/>.
+        /// </returns>
+        public static bool IsNullOrWhiteSpace(this string value)
+        {
+#if NET35
+            if (value == null) return true;
+
+            for (int i = 0; i < value.Length; i++)
+            {
+                if (!char.IsWhiteSpace(value[i])) return false;
+            }
+
+            return true;
+#else
+            return string.IsNullOrWhiteSpace(value);
+#endif
+        }
+    }
+}
\ No newline at end of file
diff --git a/QRCoder/Framework4.0Methods/String4Methods.cs b/QRCoder/Framework4.0Methods/String4Methods.cs
deleted file mode 100644
index 748c0d69..00000000
--- a/QRCoder/Framework4.0Methods/String4Methods.cs
+++ /dev/null
@@ -1,48 +0,0 @@
-using System;
-
-namespace QRCoder
-{
-    internal static class String40Methods
-    {
-        /// <summary>
-        /// The IsNullOrWhiteSpace method from Framework4.0
-        /// </summary>
-        /// <returns>
-        ///   <c>true</c> if the <paramref name="value"/> is null or white space; otherwise, <c>false</c>.
-        /// </returns>
-        public static bool IsNullOrWhiteSpace(String value)
-        {
-            if (value == null) return true;
-
-            for (int i = 0; i < value.Length; i++)
-            {
-                if (!Char.IsWhiteSpace(value[i])) return false;
-            }
-
-            return true;
-        }
-
-        public static string ReverseString(string str)
-        {
-            char[] chars = str.ToCharArray();
-            char[] result = new char[chars.Length];
-            for (int i = 0, j = str.Length - 1; i < str.Length; i++, j--)
-            {
-                result[i] = chars[j];
-            }
-            return new string(result);
-        }
-
-        public static bool IsAllDigit(string str)
-        {
-            foreach (var c in str)
-            {
-                if (!char.IsDigit(c))
-                {
-                    return false;
-                }
-            }
-            return true;
-        }
-    }
-}
\ No newline at end of file
diff --git a/QRCoder/PayloadGenerator.cs b/QRCoder/PayloadGenerator.cs
index bf9d22ce..bddd084b 100644
--- a/QRCoder/PayloadGenerator.cs
+++ b/QRCoder/PayloadGenerator.cs
@@ -2034,7 +2034,7 @@ private string TimeToString()
 
             private void ProcessCommonFields(StringBuilder sb)
             {
-                if (String40Methods.IsNullOrWhiteSpace(Secret))
+                if (Secret.IsNullOrWhiteSpace())
                 {
                     throw new Exception("Secret must be a filled out base32 encoded string");
                 }
@@ -2043,7 +2043,7 @@ private void ProcessCommonFields(StringBuilder sb)
                 string escapedLabel = null;
                 string label = null;
 
-                if (!String40Methods.IsNullOrWhiteSpace(Issuer))
+                if (!Issuer.IsNullOrWhiteSpace())
                 {
                     if (Issuer.Contains(":"))
                     {
@@ -2052,7 +2052,7 @@ private void ProcessCommonFields(StringBuilder sb)
                     escapedIssuer = Uri.EscapeDataString(Issuer);
                 }
 
-                if (!String40Methods.IsNullOrWhiteSpace(Label))
+                if (!Label.IsNullOrWhiteSpace())
                 {
                     if (Label.Contains(":"))
                     {
diff --git a/QRCoder/QRCodeData.cs b/QRCoder/QRCodeData.cs
index e9b8a571..dbb0f06c 100644
--- a/QRCoder/QRCodeData.cs
+++ b/QRCoder/QRCodeData.cs
@@ -1,14 +1,11 @@
+using System;
 using System.Collections;
 using System.Collections.Generic;
-using System.Linq;
+using System.IO;
+using System.IO.Compression;
 
 namespace QRCoder
 {
-    using QRCoder.Framework4._0Methods;
-    using System;
-    using System.IO;
-    using System.IO.Compression;
-
     public class QRCodeData : IDisposable
     {
         public List<BitArray> ModuleMatrix { get; set; }
@@ -48,7 +45,7 @@ public QRCodeData(byte[] rawData, Compression compressMode)
                     {
                         using (var dstream = new DeflateStream(input, CompressionMode.Decompress))
                         {
-                            Stream4Methods.CopyTo(dstream, output);
+                            dstream.CopyTo(output);
                         }
                         bytes = new List<byte>(output.ToArray());
                     }
@@ -62,7 +59,7 @@ public QRCodeData(byte[] rawData, Compression compressMode)
                     {
                         using (var dstream = new GZipStream(input, CompressionMode.Decompress))
                         {
-                            Stream4Methods.CopyTo(dstream, output);
+                            dstream.CopyTo(output);
                         }
                         bytes = new List<byte>(output.ToArray());
                     }