diff --git a/Semantics.Strings.Identifiers/Iban.cs b/Semantics.Strings.Identifiers/Iban.cs
index 41331579..ff44ac15 100644
--- a/Semantics.Strings.Identifiers/Iban.cs
+++ b/Semantics.Strings.Identifiers/Iban.cs
@@ -2,6 +2,9 @@
 
 namespace ktsu.Semantics.Strings.Identifiers;
 
+using System.Linq;
+using System.Text;
+
 using ktsu.Semantics.Strings;
 
 /// <summary>
@@ -12,12 +15,20 @@ namespace ktsu.Semantics.Strings.Identifiers;
 [IsIban]
 public sealed record Iban : SemanticString<Iban>
 {
-	/// <summary>Normalizes the input by stripping spaces and uppercasing.</summary>
+	/// <summary>
+	/// Normalizes the input by stripping all whitespace (spaces, tabs, line breaks) and uppercasing.
+	/// </summary>
 	/// <param name="input">The raw input string.</param>
 	/// <returns>The canonical IBAN string.</returns>
 	protected override string MakeCanonical(string input)
 	{
 		Ensure.NotNull(input);
-		return input.Replace(" ", string.Empty).ToUpperInvariant();
+		StringBuilder canonical = new(input.Length);
+		foreach (char c in input.Where(static ch => !char.IsWhiteSpace(ch)))
+		{
+			canonical.Append(char.ToUpperInvariant(c));
+		}
+
+		return canonical.ToString();
 	}
 }
diff --git a/Semantics.Strings.Identifiers/IsIbanAttribute.cs b/Semantics.Strings.Identifiers/IsIbanAttribute.cs
index 233a0f38..e69f8978 100644
--- a/Semantics.Strings.Identifiers/IsIbanAttribute.cs
+++ b/Semantics.Strings.Identifiers/IsIbanAttribute.cs
@@ -21,7 +21,7 @@ public sealed class IsIbanAttribute : NativeSemanticStringValidationAttribute
 
 	private sealed class IbanValidator : ValidationAdapter
 	{
-		private const string Pattern = "^[A-Z]{2}[0-9]{2}[A-Z0-9]+$";
+		private const string Pattern = "^[A-Z]{2}[0-9]{2}[A-Z0-9]+\\z";
 
 		protected override ValidationResult ValidateValue(string value)
 		{
diff --git a/Semantics.Strings.Identifiers/IsUlidAttribute.cs b/Semantics.Strings.Identifiers/IsUlidAttribute.cs
index 0a380eb5..03e3b2a6 100644
--- a/Semantics.Strings.Identifiers/IsUlidAttribute.cs
+++ b/Semantics.Strings.Identifiers/IsUlidAttribute.cs
@@ -20,7 +20,7 @@ public sealed class IsUlidAttribute : NativeSemanticStringValidationAttribute
 
 	private sealed class UlidValidator : ValidationAdapter
 	{
-		private const string Pattern = "^[0-7][0-9A-HJKMNP-TV-Z]{25}$";
+		private const string Pattern = "^[0-7][0-9A-HJKMNP-TV-Z]{25}\\z";
 
 		protected override ValidationResult ValidateValue(string value) =>
 			Regex.IsMatch(value, Pattern, RegexOptions.None, TimeSpan.FromSeconds(1))
diff --git a/Semantics.Strings.Identifiers/IsUuidAttribute.cs b/Semantics.Strings.Identifiers/IsUuidAttribute.cs
index 79c19a92..c315feef 100644
--- a/Semantics.Strings.Identifiers/IsUuidAttribute.cs
+++ b/Semantics.Strings.Identifiers/IsUuidAttribute.cs
@@ -20,7 +20,7 @@ public sealed class IsUuidAttribute : NativeSemanticStringValidationAttribute
 
 	private sealed class UuidValidator : ValidationAdapter
 	{
-		private const string Pattern = "^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$";
+		private const string Pattern = "^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\\z";
 
 		protected override ValidationResult ValidateValue(string value) =>
 			Regex.IsMatch(value, Pattern, RegexOptions.None, TimeSpan.FromSeconds(1))
diff --git a/Semantics.Test/Identifiers/IbanTests.cs b/Semantics.Test/Identifiers/IbanTests.cs
index 4779ec32..520016c9 100644
--- a/Semantics.Test/Identifiers/IbanTests.cs
+++ b/Semantics.Test/Identifiers/IbanTests.cs
@@ -44,4 +44,24 @@ public void Create_Empty_Throws()
 	{
 		Assert.ThrowsExactly<ArgumentException>(() => Iban.Create(string.Empty));
 	}
+
+	[TestMethod]
+	[DataRow("GB67WEST12345698765432\n")]
+	[DataRow("GB67WEST12345698765432\r\n")]
+	public void Create_InvalidChecksumWithTrailingNewline_Throws(string input)
+	{
+		Assert.ThrowsExactly<ArgumentException>(() => Iban.Create(input));
+	}
+
+	[TestMethod]
+	[DataRow("GB82WEST12345698765432\n")]
+	[DataRow("GB82WEST12345698765432\t")]
+	[DataRow("\tGB82WEST12345698765432\r\n")]
+	[DataRow("GB82 WEST 1234 5698 7654 32\n")]
+	[DataRow("GB82\u00A0WEST\u00A012345698765432")]
+	public void Create_ValidIbanWithWhitespace_StripsItAndValidates(string input)
+	{
+		Iban iban = Iban.Create(input);
+		Assert.AreEqual("GB82WEST12345698765432", iban.WeakString);
+	}
 }
diff --git a/Semantics.Test/Identifiers/UlidTests.cs b/Semantics.Test/Identifiers/UlidTests.cs
index 3041b62b..a5c51c9a 100644
--- a/Semantics.Test/Identifiers/UlidTests.cs
+++ b/Semantics.Test/Identifiers/UlidTests.cs
@@ -2,6 +2,7 @@
 
 namespace ktsu.Semantics.Test.Identifiers;
 
+using ktsu.Semantics.Strings;
 using ktsu.Semantics.Strings.Identifiers;
 
 [TestClass]
@@ -44,4 +45,19 @@ public void Create_Empty_Throws()
 	{
 		Assert.ThrowsExactly<ArgumentException>(() => Ulid.Create(string.Empty));
 	}
+
+	// Ulid trims its input, which hides the attribute's own anchoring; a type that applies [IsUlid]
+	// without canonicalizing sees the raw value.
+	[IsUlid]
+	[System.Diagnostics.CodeAnalysis.SuppressMessage("Performance", "CA1812", Justification = "Used via generic type references")]
+	private sealed partial record UntrimmedUlid : SemanticString<UntrimmedUlid> { }
+
+	[TestMethod]
+	[DataRow("01ARZ3NDEKTSV4RRFFQ69G5FAV\n")]
+	[DataRow("01ARZ3NDEKTSV4RRFFQ69G5FAV\r\n")]
+	public void IsUlid_OnUntrimmedType_RejectsTrailingNewline(string input)
+	{
+		Assert.ThrowsExactly<ArgumentException>(() => SemanticString<UntrimmedUlid>.Create<UntrimmedUlid>(input));
+		Assert.AreEqual("01ARZ3NDEKTSV4RRFFQ69G5FAV", SemanticString<UntrimmedUlid>.Create<UntrimmedUlid>("01ARZ3NDEKTSV4RRFFQ69G5FAV").WeakString);
+	}
 }
diff --git a/Semantics.Test/Identifiers/UuidTests.cs b/Semantics.Test/Identifiers/UuidTests.cs
index e2952aad..cc031556 100644
--- a/Semantics.Test/Identifiers/UuidTests.cs
+++ b/Semantics.Test/Identifiers/UuidTests.cs
@@ -2,6 +2,7 @@
 
 namespace ktsu.Semantics.Test.Identifiers;
 
+using ktsu.Semantics.Strings;
 using ktsu.Semantics.Strings.Identifiers;
 
 [TestClass]
@@ -62,4 +63,19 @@ public void As_RoundTrip_PreservesValue()
 		Assert.AreEqual(uuid, roundTripped);
 		Assert.AreEqual(uuid.WeakString, roundTripped.WeakString);
 	}
+
+	// Uuid trims its input, which hides the attribute's own anchoring; a type that applies [IsUuid]
+	// without canonicalizing sees the raw value.
+	[IsUuid]
+	[System.Diagnostics.CodeAnalysis.SuppressMessage("Performance", "CA1812", Justification = "Used via generic type references")]
+	private sealed partial record UntrimmedUuid : SemanticString<UntrimmedUuid> { }
+
+	[TestMethod]
+	[DataRow("123e4567-e89b-12d3-a456-426614174000\n")]
+	[DataRow("123e4567-e89b-12d3-a456-426614174000\r\n")]
+	public void IsUuid_OnUntrimmedType_RejectsTrailingNewline(string input)
+	{
+		Assert.ThrowsExactly<ArgumentException>(() => SemanticString<UntrimmedUuid>.Create<UntrimmedUuid>(input));
+		Assert.AreEqual("123e4567-e89b-12d3-a456-426614174000", SemanticString<UntrimmedUuid>.Create<UntrimmedUuid>("123e4567-e89b-12d3-a456-426614174000").WeakString);
+	}
 }