diff --git a/src/Tmds.DBus.Protocol/MessageWriter.Basic.cs b/src/Tmds.DBus.Protocol/MessageWriter.Basic.cs
index bdf3da9..cc33aa0 100644
--- a/src/Tmds.DBus.Protocol/MessageWriter.Basic.cs
+++ b/src/Tmds.DBus.Protocol/MessageWriter.Basic.cs
@@ -56,91 +56,91 @@ public void WriteSignature(string s)
 
     public void WriteVariantBool(bool value)
     {
-        WriteSignature(ProtocolConstants.BooleanSignature);
+        WriteSignature(Signature.Boolean);
         WriteBool(value);
     }
 
     public void WriteVariantByte(byte value)
     {
-        WriteSignature(ProtocolConstants.ByteSignature);
+        WriteSignature(Signature.Byte);
         WriteByte(value);
     }
 
     public void WriteVariantInt16(short value)
     {
-        WriteSignature(ProtocolConstants.Int16Signature);
+        WriteSignature(Signature.Int16);
         WriteInt16(value);
     }
 
     public void WriteVariantUInt16(ushort value)
     {
-        WriteSignature(ProtocolConstants.UInt16Signature);
+        WriteSignature(Signature.UInt16);
         WriteUInt16(value);
     }
 
     public void WriteVariantInt32(int value)
     {
-        WriteSignature(ProtocolConstants.Int32Signature);
+        WriteSignature(Signature.Int32);
         WriteInt32(value);
     }
 
     public void WriteVariantUInt32(uint value)
     {
-        WriteSignature(ProtocolConstants.UInt32Signature);
+        WriteSignature(Signature.UInt32);
         WriteUInt32(value);
     }
 
     public void WriteVariantInt64(long value)
     {
-        WriteSignature(ProtocolConstants.Int64Signature);
+        WriteSignature(Signature.Int64);
         WriteInt64(value);
     }
 
     public void WriteVariantUInt64(ulong value)
     {
-        WriteSignature(ProtocolConstants.UInt64Signature);
+        WriteSignature(Signature.UInt64);
         WriteUInt64(value);
     }
 
     public void WriteVariantDouble(double value)
     {
-        WriteSignature(ProtocolConstants.DoubleSignature);
+        WriteSignature(Signature.Double);
         WriteDouble(value);
     }
 
     public void WriteVariantString(scoped ReadOnlySpan<byte> value)
     {
-        WriteSignature(ProtocolConstants.StringSignature);
+        WriteSignature(Signature.String);
         WriteString(value);
     }
 
     public void WriteVariantSignature(scoped ReadOnlySpan<byte> value)
     {
-        WriteSignature(ProtocolConstants.SignatureSignature);
+        WriteSignature(Signature.Sig);
         WriteSignature(value);
     }
 
     public void WriteVariantObjectPath(scoped ReadOnlySpan<byte> value)
     {
-        WriteSignature(ProtocolConstants.ObjectPathSignature);
+        WriteSignature(Signature.ObjectPath);
         WriteObjectPath(value);
     }
 
     public void WriteVariantString(string value)
     {
-        WriteSignature(ProtocolConstants.StringSignature);
+        WriteSignature(Signature.String);
         WriteString(value);
     }
 
     public void WriteVariantSignature(string value)
     {
-        WriteSignature(ProtocolConstants.SignatureSignature);
+        WriteSignature(Signature.Sig);
         WriteSignature(value);
     }
 
     public void WriteVariantObjectPath(string value)
     {
-        WriteSignature(ProtocolConstants.ObjectPathSignature);
+        WriteSignature(Signature.ObjectPath);
         WriteObjectPath(value);
     }
 
diff --git a/src/Tmds.DBus.Protocol/MessageWriter.Handle.cs b/src/Tmds.DBus.Protocol/MessageWriter.Handle.cs
index a473fea..f85a0d6 100644
--- a/src/Tmds.DBus.Protocol/MessageWriter.Handle.cs
+++ b/src/Tmds.DBus.Protocol/MessageWriter.Handle.cs
@@ -11,7 +11,7 @@ public void WriteHandle(SafeHandle value)
 
     public void WriteVariantHandle(SafeHandle value)
     {
-        WriteSignature(ProtocolConstants.UnixFdSignature);
+        WriteSignature(Signature.UnixFd);
         WriteHandle(value);
     }
 
diff --git a/src/Tmds.DBus.Protocol/MessageWriter.Header.cs b/src/Tmds.DBus.Protocol/MessageWriter.Header.cs
index f00b973..98629d1 100644
--- a/src/Tmds.DBus.Protocol/MessageWriter.Header.cs
+++ b/src/Tmds.DBus.Protocol/MessageWriter.Header.cs
@@ -120,7 +120,7 @@ public void WriteError(
         {
             WriteStructureStart();
             WriteByte((byte)MessageHeader.Signature);
-            WriteVariantSignature(ProtocolConstants.StringSignature);
+            WriteVariantSignature(Signature.String);
         }
 
         WriteHeaderEnd(start);
diff --git a/src/Tmds.DBus.Protocol/ProtocolConstants.cs b/src/Tmds.DBus.Protocol/ProtocolConstants.cs
index b9d0537..6b37d09 100644
--- a/src/Tmds.DBus.Protocol/ProtocolConstants.cs
+++ b/src/Tmds.DBus.Protocol/ProtocolConstants.cs
@@ -3,23 +3,6 @@ namespace Tmds.DBus.Protocol;
 static class ProtocolConstants
 {
     public const int MaxSignatureLength = 256;
-
-    // note: C# compiler treats these as static data.
-    public static ReadOnlySpan<byte> ByteSignature => new byte[] { (byte)'y' };
-    public static ReadOnlySpan<byte> BooleanSignature => new byte[] { (byte)'b' };
-    public static ReadOnlySpan<byte> Int16Signature => new byte[] { (byte)'n' };
-    public static ReadOnlySpan<byte> UInt16Signature => new byte[] { (byte)'q' };
-    public static ReadOnlySpan<byte> Int32Signature => new byte[] { (byte)'i' };
-    public static ReadOnlySpan<byte> UInt32Signature => new byte[] { (byte)'u' };
-    public static ReadOnlySpan<byte> Int64Signature => new byte[] { (byte)'x' };
-    public static ReadOnlySpan<byte> UInt64Signature => new byte[] { (byte)'t' };
-    public static ReadOnlySpan<byte> DoubleSignature => new byte[] { (byte)'d' };
-    public static ReadOnlySpan<byte> UnixFdSignature => new byte[] { (byte)'h' };
-    public static ReadOnlySpan<byte> StringSignature => new byte[] { (byte)'s' };
-    public static ReadOnlySpan<byte> ObjectPathSignature => new byte[] { (byte)'o' };
-    public static ReadOnlySpan<byte> SignatureSignature => new byte[] { (byte)'g' };
-    public static ReadOnlySpan<byte> VariantSignature => new byte[] { (byte)'v' };
-
     public const int StructAlignment = 8;
     public const int UInt32Alignment = 4;
 
diff --git a/src/Tmds.DBus.Protocol/VariantValue.cs b/src/Tmds.DBus.Protocol/VariantValue.cs
index cc43e15..d5c1ee0 100644
--- a/src/Tmds.DBus.Protocol/VariantValue.cs
+++ b/src/Tmds.DBus.Protocol/VariantValue.cs
@@ -1719,7 +1719,7 @@ private void WriteValueTo(ref MessageWriter writer, int nestingOffset)
         nesting += nestingOffset;
         while (nesting > 1)
         {
-            writer.WriteSignature(ProtocolConstants.VariantSignature);
+            writer.WriteSignature(Protocol.Signature.Variant);
             nesting--;
         }
         if (nesting == 1)