diff --git a/java/debugger/impl/src/com/intellij/debugger/actions/ThreadDumpAction.java b/java/debugger/impl/src/com/intellij/debugger/actions/ThreadDumpAction.java
index 84902b7cc0e5..78c838d184fd 100644
--- a/java/debugger/impl/src/com/intellij/debugger/actions/ThreadDumpAction.java
+++ b/java/debugger/impl/src/com/intellij/debugger/actions/ThreadDumpAction.java
@@ -157,14 +157,17 @@ public class ThreadDumpAction extends AnAction implements AnAction.TransparentUp
         hasEmptyStack = frames.size() == 0;
 
         final TIntObjectHashMap<List<ObjectReference>> lockedAt = new TIntObjectHashMap<>();
-        if (vmProxy.canGetMonitorFrameInfo() && vmProxy.canBeModified()) {
-          for (MonitorInfo info : threadReference.ownedMonitorsAndFrames()) {
-            final int stackDepth = info.stackDepth();
-            List<ObjectReference> monitors;
-            if ((monitors = lockedAt.get(stackDepth)) == null) {
-              lockedAt.put(stackDepth, monitors = new SmartList<>());
+        if (vmProxy.canGetMonitorFrameInfo()) {
+          for (Object m : threadReference.ownedMonitorsAndFrames()) {
+            if (m instanceof MonitorInfo) { // see JRE-937
+              MonitorInfo info = (MonitorInfo)m;
+              final int stackDepth = info.stackDepth();
+              List<ObjectReference> monitors;
+              if ((monitors = lockedAt.get(stackDepth)) == null) {
+                lockedAt.put(stackDepth, monitors = new SmartList<>());
+              }
+              monitors.add(info.monitor());
             }
-            monitors.add(info.monitor());
           }
         }