diff --git a/libjava/include/jvmti-int.h b/libjava/include/jvmti-int.h
index 822163afa0d..f868655734a 100644
--- a/libjava/include/jvmti-int.h
+++ b/libjava/include/jvmti-int.h
@@ -37,6 +37,10 @@ executable file might be covered by the GNU General Public License. */
    False means no JVMTI environment requested that event type. */
 namespace JVMTI
 {
+  // Is JVMTI enabled? (i.e., any jvmtiEnv created?)
+  extern bool enabled;
+
+  // Event notifications
   extern bool VMInit;
   extern bool VMDeath;
   extern bool ThreadStart;
diff --git a/libjava/interpret-run.cc b/libjava/interpret-run.cc
index f3687459cb4..12d0b9a5683 100644
--- a/libjava/interpret-run.cc
+++ b/libjava/interpret-run.cc
@@ -248,7 +248,27 @@ details.  */
 
 #ifdef DIRECT_THREADED
 
+#ifdef DEBUG
+#undef NEXT_INSN
+#define NEXT_INSN							\
+  do									\
+    {									\
+      if (JVMTI_REQUESTED_EVENT (SingleStep))				\
+	{								\
+	  JNIEnv *env = _Jv_GetCurrentJNIEnv ();			\
+	  jmethodID method = meth->self;				\
+	  jlocation loc = meth->insn_index (pc);			\
+	  _Jv_JVMTI_PostEvent (JVMTI_EVENT_SINGLE_STEP, thread,		\
+			       env, method, loc);			\
+	}								\
+      goto *((pc++)->insn);						\
+    }									\
+  while (0)
+#else
+#undef NEXT_INSN
 #define NEXT_INSN goto *((pc++)->insn)
+#endif
+
 #define INTVAL() ((pc++)->int_val)
 #define AVAL() ((pc++)->datum)
 
@@ -281,7 +301,22 @@ details.  */
 
 #else
 
+#ifdef DEBUG
+#define NEXT_INSN							\
+  do									\
+    {									\
+      if (JVMTI_REQUESTED_EVENT (SingleStep))				\
+	{								\
+	  JNIEnv *env = _Jv_GetCurrentJNIEnv ();			\
+	  jmethodID method = meth->self;				\
+	  jlocation loc = meth->insn_index (pc);			\
+	  _Jv_JVMTI_PostEvent (JVMTI_EVENT_SINGLE_STEP, thread,		\
+			       env, method, loc);			\
+	}								\
+      goto *(insn_target[*pc++])
+#else
 #define NEXT_INSN goto *(insn_target[*pc++])
+#endif
 
 #define GET1S() get1s (pc++)
 #define GET2S() (pc += 2, get2s (pc- 2))
diff --git a/libjava/interpret.cc b/libjava/interpret.cc
index 7e694a392a1..7e7d36d4e01 100644
--- a/libjava/interpret.cc
+++ b/libjava/interpret.cc
@@ -1297,34 +1297,34 @@ _Jv_InterpMethod::ncode ()
     {
       if (staticp)
         {
-        if (::gnu::classpath::jdwp::Jdwp::isDebugging)
-		  fun = (ffi_closure_fun)&_Jv_InterpMethod::run_synch_class_debug;
-		else
-		  fun = (ffi_closure_fun)&_Jv_InterpMethod::run_synch_class;
+	  if (JVMTI::enabled)
+	    fun = (ffi_closure_fun)&_Jv_InterpMethod::run_synch_class_debug;
+	  else
+	    fun = (ffi_closure_fun)&_Jv_InterpMethod::run_synch_class;
         }
       else
         {
-	      if (::gnu::classpath::jdwp::Jdwp::isDebugging)
-		    fun = (ffi_closure_fun)&_Jv_InterpMethod::run_synch_object_debug;
-		  else
-		  	fun = (ffi_closure_fun)&_Jv_InterpMethod::run_synch_object;
-        } 
+	  if (JVMTI::enabled)
+	    fun = (ffi_closure_fun)&_Jv_InterpMethod::run_synch_object_debug;
+	  else
+	    fun = (ffi_closure_fun)&_Jv_InterpMethod::run_synch_object;
+        }
     }
   else
     {
       if (staticp)
         {
-	      if (::gnu::classpath::jdwp::Jdwp::isDebugging)
-		    fun = (ffi_closure_fun)&_Jv_InterpMethod::run_class_debug;
-		  else
-		    fun = (ffi_closure_fun)&_Jv_InterpMethod::run_class;
+	  if (JVMTI::enabled)
+	    fun = (ffi_closure_fun)&_Jv_InterpMethod::run_class_debug;
+	  else
+	    fun = (ffi_closure_fun)&_Jv_InterpMethod::run_class;
         }
       else
         {
-	      if (::gnu::classpath::jdwp::Jdwp::isDebugging)
-		    fun = (ffi_closure_fun)&_Jv_InterpMethod::run_normal_debug;
-		  else
-		    fun = (ffi_closure_fun)&_Jv_InterpMethod::run_normal;
+	  if (JVMTI::enabled)
+	    fun = (ffi_closure_fun)&_Jv_InterpMethod::run_normal_debug;
+	  else
+	    fun = (ffi_closure_fun)&_Jv_InterpMethod::run_normal;
         }
     }
 
@@ -1680,7 +1680,12 @@ void
 _Jv_CompileMethod (_Jv_InterpMethod* method)
 {
   if (method->prepared == NULL)
-    _Jv_InterpMethod::run (NULL, NULL, method);
+    {
+      if (JVMTI::enabled)
+	_Jv_InterpMethod::run_debug (NULL, NULL, method);
+      else
+      _Jv_InterpMethod::run (NULL, NULL, method);
+    }
 }
 #endif // DIRECT_THREADED
 
diff --git a/libjava/jvmti.cc b/libjava/jvmti.cc
index c9c7e7ba731..2e32634b202 100644
--- a/libjava/jvmti.cc
+++ b/libjava/jvmti.cc
@@ -44,6 +44,10 @@ static void check_enabled_event (jvmtiEvent);
 
 namespace JVMTI
 {
+  // Is JVMTI enabled? (i.e., any jvmtiEnv created?)
+  bool enabled;
+
+  // Event notifications
   bool VMInit = false;
   bool VMDeath = false;
   bool ThreadStart = false;
@@ -1754,6 +1758,10 @@ _Jv_GetJVMTIEnv (void)
       }
   }
 
+  /* Mark JVMTI active. This is used to force the interpreter
+     to use either debugging or non-debugging code. Once JVMTI
+     has been enabled, the non-debug interpreter cannot be used. */
+  JVMTI::enabled = true;
   return env;
 }