src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/debugger/DebuggerBase.java

@@ -399,11 +399,11 @@
      throws UnmappedAddressException, UnalignedAddressException {
      long value;
      if (VM.getVM().isCompactObjectHeadersEnabled()) {
        // With compact headers, the compressed Klass* is currently read from the mark
        // word. We need to load the whole mark, and shift the upper parts.
-       value = readCInteger(address, machDesc.getAddressSize(), true);
+       value = readCInteger(address, jintSize, true);
        value = value >>> Mark.getKlassShift();
      } else {
        value = readCInteger(address, getKlassPtrSize(), true);
      }
      if (value != 0) {