diff --git a/src/main/java/io/usethesource/vallang/io/binary/stream/Compressor.java b/src/main/java/io/usethesource/vallang/io/binary/stream/Compressor.java
index 6064136f..47df58ef 100644
--- a/src/main/java/io/usethesource/vallang/io/binary/stream/Compressor.java
+++ b/src/main/java/io/usethesource/vallang/io/binary/stream/Compressor.java
@@ -57,8 +57,8 @@ public void setLevel(int level) {
                 result.setLevel(level);
                 return result;
             }
-            case Header.Compression.XZ: {
-                throw new IOException("XZ compression is not supported anymore, please use an older version of rascal/vallang to open the file and store it with a different level of compression");
+            case Header.Compression.UNSUPPORTED_XZ: {
+                throw new UnsupportedOperationException("XZ compression is not supported anymore, please use an older version of rascal/vallang to open the file and store it with a different level of compression");
             }
             case Header.Compression.ZSTD: {
                 return new ZstdOutputStream(rawStream, level);
@@ -74,8 +74,8 @@ public static InputStream wrapStream(InputStream raw, int algorithm) throws IOEx
                 return raw;
             case Header.Compression.GZIP:
                 return new GZIPInputStream(raw);
-            case Header.Compression.XZ:
-                throw new IOException("XZ compression is not supported anymore, please use an older version of rascal/vallang to open the file and store it with a different level of compression");
+            case Header.Compression.UNSUPPORTED_XZ:
+                throw new UnsupportedOperationException("XZ compression is not supported anymore, please use an older version of rascal/vallang to open the file and store it with a different level of compression");
             case Header.Compression.ZSTD:
                 if (Compressor.zstdAvailable()) {
                     if (raw instanceof ByteBufferInputStream && ((ByteBufferInputStream)raw).getByteBuffer().isDirect()) {
diff --git a/src/main/java/io/usethesource/vallang/io/binary/stream/Header.java b/src/main/java/io/usethesource/vallang/io/binary/stream/Header.java
index 6e9f58ee..7ca9ed79 100644
--- a/src/main/java/io/usethesource/vallang/io/binary/stream/Header.java
+++ b/src/main/java/io/usethesource/vallang/io/binary/stream/Header.java
@@ -17,8 +17,8 @@
     public static final class Compression {
         public static final byte NONE = 0;
         public static final byte GZIP = 1;
-        /** Not used anymore, it was never used, and we're cutting down on dependencies */
-        public static final byte XZ = 2;
+        /** Never officially available, but still reserved */
+        public static final byte UNSUPPORTED_XZ = 2;
         public static final byte ZSTD = 3;
     }
 
diff --git a/src/main/java/io/usethesource/vallang/io/binary/stream/IValueInputStream.java b/src/main/java/io/usethesource/vallang/io/binary/stream/IValueInputStream.java
index 4abac8f0..376bec90 100644
--- a/src/main/java/io/usethesource/vallang/io/binary/stream/IValueInputStream.java
+++ b/src/main/java/io/usethesource/vallang/io/binary/stream/IValueInputStream.java
@@ -51,7 +51,7 @@ public IValueInputStream(InputStream in, IValueFactory vf, Supplier<TypeStore> t
             read += in.read(currentHeader, read, currentHeader.length - read);
         }
         if (!Arrays.equals(currentHeader, Header.MAIN)) {
-            throw new IOException("Incorrect file header, are you sure this is a valid file containing a serialized value?");
+            throw new IOException("Incorrect file header, expected: [" + toHex(Header.MAIN) + "] but found: [" + toHex(currentHeader) + "]");
         }
 
         int compression = in.read();
@@ -60,6 +60,15 @@ public IValueInputStream(InputStream in, IValueFactory vf, Supplier<TypeStore> t
     }
     
 
+    private String toHex(byte[] main) {
+        String result = "";
+        for (byte b : main) {
+            result += String.format("%#04x ", b);
+        }
+        return result.trim();
+    }
+
+
     public IValueInputStream(FileChannel channel, IValueFactory vf, Supplier<TypeStore> typeStoreSupplier) throws IOException {
         this(new FileChannelDirectInputStream(channel), vf, typeStoreSupplier);
     }