diff --git a/api_guard.include.md b/api_guard.include.md
index 0bcd4002..44f3e20c 100644
--- a/api_guard.include.md
+++ b/api_guard.include.md
@@ -16,13 +16,13 @@
  * `T NotNullOrEmpty<T>(T) where T : Collections.IEnumerable`
  * `Memory<Char> NotNullOrEmpty(Nullable<Memory<Char>>)`
  * `ReadOnlyMemory<Char> NotNullOrEmpty(Nullable<ReadOnlyMemory<Char>>)`
- * `String NotNullOrWhitespace(String)`
- * `Memory<Char> NotNullOrWhitespace(Nullable<Memory<Char>>)`
- * `ReadOnlyMemory<Char> NotNullOrWhitespace(Nullable<ReadOnlyMemory<Char>>)`
- * `void NotWhitespace(String)`
- * `void NotWhitespace(ReadOnlySpan<Char>)`
- * `void NotWhitespace(Nullable<Memory<Char>>)`
- * `void NotWhitespace(Nullable<ReadOnlyMemory<Char>>)`
- * `void NotWhitespace(Span<Char>)`
+ * `String NotNullOrWhiteSpace(String)`
+ * `Memory<Char> NotNullOrWhiteSpace(Nullable<Memory<Char>>)`
+ * `ReadOnlyMemory<Char> NotNullOrWhiteSpace(Nullable<ReadOnlyMemory<Char>>)`
+ * `void NotWhiteSpace(String)`
+ * `void NotWhiteSpace(ReadOnlySpan<Char>)`
+ * `void NotWhiteSpace(Nullable<Memory<Char>>)`
+ * `void NotWhiteSpace(Nullable<ReadOnlyMemory<Char>>)`
+ * `void NotWhiteSpace(Span<Char>)`
 
 
diff --git a/api_list.include.md b/api_list.include.md
index 700a0c9d..9b986ef1 100644
--- a/api_list.include.md
+++ b/api_list.include.md
@@ -311,7 +311,7 @@
  * `StringBuilder AppendLine(StringBuilder, IFormatProvider, StringBuilder/AppendInterpolatedStringHandler&)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.stringbuilder.appendline#system-text-stringbuilder-appendline(system-iformatprovider-system-text-stringbuilder-appendinterpolatedstringhandler@))
  * `void CopyTo(Int32, Span<Char>, Int32)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.stringbuilder.copyto#system-text-stringbuilder-copyto(system-int32-system-span((system-char))-system-int32))
  * `Boolean Equals(ReadOnlySpan<Char>)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.stringbuilder.equals#system-text-stringbuilder-equals(system-readonlyspan((system-char))))
- * `Polyfill/ChunkEnumerator GetChunks()` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.stringbuilder.getchunks)
+ * `Polyfills.Polyfill/ChunkEnumerator GetChunks()` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.stringbuilder.getchunks)
  * `StringBuilder Replace(ReadOnlySpan<Char>, ReadOnlySpan<Char>)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.stringbuilder.replace#system-text-stringbuilder-replace(system-readonlyspan((system-char))-system-readonlyspan((system-char))))
  * `StringBuilder Replace(ReadOnlySpan<Char>, ReadOnlySpan<Char>, Int32, Int32)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.stringbuilder.replace#system-text-stringbuilder-replace(system-char-system-char-system-int32-system-int32))
 
@@ -544,14 +544,14 @@
  * `T NotNullOrEmpty<T>(T) where T : Collections.IEnumerable`
  * `Memory<Char> NotNullOrEmpty(Nullable<Memory<Char>>)`
  * `ReadOnlyMemory<Char> NotNullOrEmpty(Nullable<ReadOnlyMemory<Char>>)`
- * `String NotNullOrWhitespace(String)`
- * `Memory<Char> NotNullOrWhitespace(Nullable<Memory<Char>>)`
- * `ReadOnlyMemory<Char> NotNullOrWhitespace(Nullable<ReadOnlyMemory<Char>>)`
- * `void NotWhitespace(String)`
- * `void NotWhitespace(ReadOnlySpan<Char>)`
- * `void NotWhitespace(Nullable<Memory<Char>>)`
- * `void NotWhitespace(Nullable<ReadOnlyMemory<Char>>)`
- * `void NotWhitespace(Span<Char>)`
+ * `String NotNullOrWhiteSpace(String)`
+ * `Memory<Char> NotNullOrWhiteSpace(Nullable<Memory<Char>>)`
+ * `ReadOnlyMemory<Char> NotNullOrWhiteSpace(Nullable<ReadOnlyMemory<Char>>)`
+ * `void NotWhiteSpace(String)`
+ * `void NotWhiteSpace(ReadOnlySpan<Char>)`
+ * `void NotWhiteSpace(Nullable<Memory<Char>>)`
+ * `void NotWhiteSpace(Nullable<ReadOnlyMemory<Char>>)`
+ * `void NotWhiteSpace(Span<Char>)`
 
 
 #### TaskCompletionSource
diff --git a/readme.md b/readme.md
index 256b3249..0770fca0 100644
--- a/readme.md
+++ b/readme.md
@@ -720,7 +720,7 @@ The class `Polyfill` includes the following extension methods:
  * `StringBuilder AppendLine(StringBuilder, IFormatProvider, StringBuilder/AppendInterpolatedStringHandler&)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.stringbuilder.appendline#system-text-stringbuilder-appendline(system-iformatprovider-system-text-stringbuilder-appendinterpolatedstringhandler@))
  * `void CopyTo(Int32, Span<Char>, Int32)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.stringbuilder.copyto#system-text-stringbuilder-copyto(system-int32-system-span((system-char))-system-int32))
  * `Boolean Equals(ReadOnlySpan<Char>)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.stringbuilder.equals#system-text-stringbuilder-equals(system-readonlyspan((system-char))))
- * `Polyfill/ChunkEnumerator GetChunks()` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.stringbuilder.getchunks)
+ * `Polyfills.Polyfill/ChunkEnumerator GetChunks()` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.stringbuilder.getchunks)
  * `StringBuilder Replace(ReadOnlySpan<Char>, ReadOnlySpan<Char>)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.stringbuilder.replace#system-text-stringbuilder-replace(system-readonlyspan((system-char))-system-readonlyspan((system-char))))
  * `StringBuilder Replace(ReadOnlySpan<Char>, ReadOnlySpan<Char>, Int32, Int32)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.text.stringbuilder.replace#system-text-stringbuilder-replace(system-char-system-char-system-int32-system-int32))
 
@@ -953,14 +953,14 @@ The class `Polyfill` includes the following extension methods:
  * `T NotNullOrEmpty<T>(T) where T : Collections.IEnumerable`
  * `Memory<Char> NotNullOrEmpty(Nullable<Memory<Char>>)`
  * `ReadOnlyMemory<Char> NotNullOrEmpty(Nullable<ReadOnlyMemory<Char>>)`
- * `String NotNullOrWhitespace(String)`
- * `Memory<Char> NotNullOrWhitespace(Nullable<Memory<Char>>)`
- * `ReadOnlyMemory<Char> NotNullOrWhitespace(Nullable<ReadOnlyMemory<Char>>)`
- * `void NotWhitespace(String)`
- * `void NotWhitespace(ReadOnlySpan<Char>)`
- * `void NotWhitespace(Nullable<Memory<Char>>)`
- * `void NotWhitespace(Nullable<ReadOnlyMemory<Char>>)`
- * `void NotWhitespace(Span<Char>)`
+ * `String NotNullOrWhiteSpace(String)`
+ * `Memory<Char> NotNullOrWhiteSpace(Nullable<Memory<Char>>)`
+ * `ReadOnlyMemory<Char> NotNullOrWhiteSpace(Nullable<ReadOnlyMemory<Char>>)`
+ * `void NotWhiteSpace(String)`
+ * `void NotWhiteSpace(ReadOnlySpan<Char>)`
+ * `void NotWhiteSpace(Nullable<Memory<Char>>)`
+ * `void NotWhiteSpace(Nullable<ReadOnlyMemory<Char>>)`
+ * `void NotWhiteSpace(Span<Char>)`
 
 
 #### TaskCompletionSource<!-- endInclude -->
@@ -1125,14 +1125,14 @@ With the equivalent Guard APIs:
  * `T NotNullOrEmpty<T>(T) where T : Collections.IEnumerable`
  * `Memory<Char> NotNullOrEmpty(Nullable<Memory<Char>>)`
  * `ReadOnlyMemory<Char> NotNullOrEmpty(Nullable<ReadOnlyMemory<Char>>)`
- * `String NotNullOrWhitespace(String)`
- * `Memory<Char> NotNullOrWhitespace(Nullable<Memory<Char>>)`
- * `ReadOnlyMemory<Char> NotNullOrWhitespace(Nullable<ReadOnlyMemory<Char>>)`
- * `void NotWhitespace(String)`
- * `void NotWhitespace(ReadOnlySpan<Char>)`
- * `void NotWhitespace(Nullable<Memory<Char>>)`
- * `void NotWhitespace(Nullable<ReadOnlyMemory<Char>>)`
- * `void NotWhitespace(Span<Char>)`
+ * `String NotNullOrWhiteSpace(String)`
+ * `Memory<Char> NotNullOrWhiteSpace(Nullable<Memory<Char>>)`
+ * `ReadOnlyMemory<Char> NotNullOrWhiteSpace(Nullable<ReadOnlyMemory<Char>>)`
+ * `void NotWhiteSpace(String)`
+ * `void NotWhiteSpace(ReadOnlySpan<Char>)`
+ * `void NotWhiteSpace(Nullable<Memory<Char>>)`
+ * `void NotWhiteSpace(Nullable<ReadOnlyMemory<Char>>)`
+ * `void NotWhiteSpace(Span<Char>)`
 
 <!-- endInclude -->
 
diff --git a/src/Polyfill/Guard_NotNullOrWhitespace.cs b/src/Polyfill/Guard_NotNullOrWhiteSpace2.cs
similarity index 93%
rename from src/Polyfill/Guard_NotNullOrWhitespace.cs
rename to src/Polyfill/Guard_NotNullOrWhiteSpace2.cs
index 901fae1f..a98dd67f 100644
--- a/src/Polyfill/Guard_NotNullOrWhitespace.cs
+++ b/src/Polyfill/Guard_NotNullOrWhiteSpace2.cs
@@ -21,7 +21,7 @@ namespace Polyfills;
 
 static partial class Guard
 {
-    public static string NotNullOrWhitespace(
+    public static string NotNullOrWhiteSpace(
         [NotNull] string? value,
         [CallerArgumentExpression("value")] string argumentName = "")
     {
@@ -47,7 +47,7 @@ public static string NotNullOrWhitespace(
     }
 
 #if FeatureMemory
-    public static Memory<char> NotNullOrWhitespace(
+    public static Memory<char> NotNullOrWhiteSpace(
         [NotNull] Memory<char>? value,
         [CallerArgumentExpression("value")] string argumentName = "")
     {
@@ -72,7 +72,7 @@ public static Memory<char> NotNullOrWhitespace(
         throw new ArgumentException("Argument cannot be whitespace.", argumentName);
     }
 
-    public static ReadOnlyMemory<char> NotNullOrWhitespace(
+    public static ReadOnlyMemory<char> NotNullOrWhiteSpace(
         [NotNull] ReadOnlyMemory<char>? value,
         [CallerArgumentExpression("value")] string argumentName = "")
     {
diff --git a/src/Polyfill/Guard_NotWhitespace.cs b/src/Polyfill/Guard_NotWhiteSpace2.cs
similarity index 94%
rename from src/Polyfill/Guard_NotWhitespace.cs
rename to src/Polyfill/Guard_NotWhiteSpace2.cs
index cfc037c3..69d1c545 100644
--- a/src/Polyfill/Guard_NotWhitespace.cs
+++ b/src/Polyfill/Guard_NotWhiteSpace2.cs
@@ -21,7 +21,7 @@ namespace Polyfills;
 
 static partial class Guard
 {
-    public static void NotWhitespace(
+    public static void NotWhiteSpace(
         string? value,
         [CallerArgumentExpression("value")] string argumentName = "")
     {
@@ -47,7 +47,7 @@ public static void NotWhitespace(
     }
 #if FeatureMemory
 
-    public static void NotWhitespace(
+    public static void NotWhiteSpace(
         ReadOnlySpan<char> value,
         [CallerArgumentExpression("value")] string argumentName = "")
     {
@@ -67,7 +67,7 @@ public static void NotWhitespace(
         throw new ArgumentException("Argument cannot be whitespace.", argumentName);
     }
 
-    public static void NotWhitespace(
+    public static void NotWhiteSpace(
         Memory<char>? value,
         [CallerArgumentExpression("value")] string argumentName = "")
     {
@@ -92,7 +92,7 @@ public static void NotWhitespace(
         throw new ArgumentException("Argument cannot be whitespace.", argumentName);
     }
 
-    public static void NotWhitespace(
+    public static void NotWhiteSpace(
         ReadOnlyMemory<char>? value,
         [CallerArgumentExpression("value")] string argumentName = "")
     {
@@ -117,7 +117,7 @@ public static void NotWhitespace(
         throw new ArgumentException("Argument cannot be whitespace.", argumentName);
     }
 
-    public static void NotWhitespace(
+    public static void NotWhiteSpace(
         Span<char> value,
         [CallerArgumentExpression("value")] string argumentName = "")
     {
diff --git a/src/Tests/GuardTests.cs b/src/Tests/GuardTests.cs
index 853fd7ae..7af5601c 100644
--- a/src/Tests/GuardTests.cs
+++ b/src/Tests/GuardTests.cs
@@ -173,18 +173,18 @@ public void NotEmpty()
     }
 
     [Test]
-    public void NotWhitespace()
+    public void NotWhiteSpace()
     {
         Assert.Throws<ArgumentException>(
-            () => Guard.NotWhitespace(" \t"));
+            () => Guard.NotWhiteSpace(" \t"));
         Assert.Throws<ArgumentException>(
-            () => Guard.NotWhitespace(string.Empty));
+            () => Guard.NotWhiteSpace(string.Empty));
 #if FeatureMemory
         Span<char> buffer = [];
         var spanCaught = false;
         try
         {
-            Guard.NotWhitespace(buffer);
+            Guard.NotWhiteSpace(buffer);
         }
         catch (ArgumentException)
         {
@@ -192,39 +192,39 @@ public void NotWhitespace()
         }
         Assert.True(spanCaught);
         Assert.Throws<ArgumentException>(
-            () => Guard.NotWhitespace(Memory<char>.Empty));
+            () => Guard.NotWhiteSpace(Memory<char>.Empty));
         Assert.Throws<ArgumentException>(
-            () => Guard.NotWhitespace(Span<char>.Empty));
+            () => Guard.NotWhiteSpace(Span<char>.Empty));
         Assert.Throws<ArgumentException>(
-            () => Guard.NotWhitespace(ReadOnlyMemory<char>.Empty));
-        Guard.NotWhitespace((Memory<char>?) null!);
-        Guard.NotWhitespace((ReadOnlyMemory<char>?) null!);
+            () => Guard.NotWhiteSpace(ReadOnlyMemory<char>.Empty));
+        Guard.NotWhiteSpace((Memory<char>?) null!);
+        Guard.NotWhiteSpace((ReadOnlyMemory<char>?) null!);
 #endif
         // ReSharper disable once RedundantCast
-        Guard.NotWhitespace((string)null!);
-        Guard.NotWhitespace("value");
+        Guard.NotWhiteSpace((string)null!);
+        Guard.NotWhiteSpace("value");
     }
 
     [Test]
-    public void NotNullOrWhitespace()
+    public void NotNullOrWhiteSpace()
     {
 #if FeatureMemory
         Assert.Throws<ArgumentException>(
-            () => Guard.NotNullOrWhitespace(Memory<char>.Empty));
+            () => Guard.NotNullOrWhiteSpace(Memory<char>.Empty));
         Assert.Throws<ArgumentNullException>(
-            () => Guard.NotNullOrWhitespace((Memory<char>?)null));
+            () => Guard.NotNullOrWhiteSpace((Memory<char>?)null));
         Assert.Throws<ArgumentNullException>(
-            () => Guard.NotNullOrWhitespace((ReadOnlyMemory<char>?)null));
+            () => Guard.NotNullOrWhiteSpace((ReadOnlyMemory<char>?)null));
         Assert.Throws<ArgumentException>(
-            () => Guard.NotNullOrWhitespace(ReadOnlyMemory<char>.Empty));
+            () => Guard.NotNullOrWhiteSpace(ReadOnlyMemory<char>.Empty));
 #endif
         Assert.Throws<ArgumentException>(
-            () => Guard.NotNullOrWhitespace(" \t"));
+            () => Guard.NotNullOrWhiteSpace(" \t"));
         Assert.Throws<ArgumentNullException>(
             // ReSharper disable once RedundantCast
-            () => Guard.NotNullOrWhitespace((string)null!));
+            () => Guard.NotNullOrWhiteSpace((string)null!));
         Assert.Throws<ArgumentException>(
-            () => Guard.NotNullOrWhitespace(string.Empty));
-        Guard.NotNullOrWhitespace("value");
+            () => Guard.NotNullOrWhiteSpace(string.Empty));
+        Guard.NotNullOrWhiteSpace("value");
     }
 }
\ No newline at end of file