--- old/src/jdk.internal.vm.compiler/share/classes/org.graalvm.graphio/src/org/graalvm/graphio/GraphProtocol.java	2019-05-04 02:43:40.580096923 +0200
+++ new/src/jdk.internal.vm.compiler/share/classes/org.graalvm.graphio/src/org/graalvm/graphio/GraphProtocol.java	2019-05-04 02:43:40.176094556 +0200
@@ -75,6 +75,9 @@
 
     private static final byte[] MAGIC_BYTES = {'B', 'I', 'G', 'V'};
 
+    private static final int MAJOR_VERSION = 6;
+    private static final int MINOR_VERSION = 1;
+
     private final ConstantPool constantPool;
     private final ByteBuffer buffer;
     private final WritableByteChannel channel;
@@ -84,7 +87,7 @@
     private boolean printing;
 
     GraphProtocol(WritableByteChannel channel, int major, int minor, boolean embedded) throws IOException {
-        if (major > 6 || (major == 6 && minor > 0)) {
+        if (major > MAJOR_VERSION || (major == MAJOR_VERSION && minor > MINOR_VERSION)) {
             throw new IllegalArgumentException("Unrecognized version " + major + "." + minor);
         }
         this.versionMajor = major;