diff --git a/gnu/expr/Language.java b/gnu/expr/Language.java
index 0447af9..2bd0663 100644
--- a/gnu/expr/Language.java
+++ b/gnu/expr/Language.java
@@ -52,6 +52,7 @@ public abstract class Language
         CheckConsole.prompt1.set(language.getPrimaryPrompt());
     if (CheckConsole.prompt2.get(null) == null)
         CheckConsole.prompt2.set(language.getSecondaryPrompt());
+    new Error("setCurL:"+language+" th:"+Thread.currentThread()+" p1:"+CheckConsole.prompt1.get(null)+" p2:"+CheckConsole.prompt2.get(null)).printStackTrace();
   }
 
   public static Language setSaveCurrent (Language language)
diff --git a/kawa/DomTermBackend.java b/kawa/DomTermBackend.java
index feb4f81..0492b0b 100644
--- a/kawa/DomTermBackend.java
+++ b/kawa/DomTermBackend.java
@@ -129,6 +129,7 @@ public class DomTermBackend extends Backend implements Runnable {
     }
 
     public void run() {
+        new Error("DomTerm.run th:"+Thread.currentThread()+" p1:"+CheckConsole.prompt1.get(null)+" p2:"+CheckConsole.prompt2.get(null)).printStackTrace();
         Writer errWriter = new DomTermErrorWriter(termWriter);
         OutPort outp = new OutPort(termWriter, true, true,
                                    Path.valueOf("/dev/stdout"));