diff --git a/Python/pystate.c b/Python/pystate.c
index a18a159b551..18dd3276f00 100644
--- a/Python/pystate.c
+++ b/Python/pystate.c
@@ -231,7 +231,7 @@ PyStatus
 _PyInterpreterState_Enable(_PyRuntimeState *runtime)
 {
     struct pyinterpreters *interpreters = &runtime->interpreters;
-    interpreters->next_id = 0;
+    interpreters->next_id = 1;
 
     /* Py_Finalize() calls _PyRuntimeState_Fini() which clears the mutex.
        Create a new mutex if needed. */
@@ -350,7 +350,7 @@ PyInterpreterState_New(void)
     if (old_head == NULL) {
         // We are creating the main interpreter.
         assert(interpreters->main == NULL);
-        assert(id == 0);
+        assert(id == 1);
 
         interp = &runtime->_main_interpreter;
         assert(interp->id == 0);
diff --git a/Python/traceback.c b/Python/traceback.c
index 4d6cbaae8da..86c6853369c 100644
--- a/Python/traceback.c
+++ b/Python/traceback.c
@@ -25,9 +25,14 @@
 #define OFF(x) offsetof(PyTracebackObject, x)
 
 #define PUTS(fd, str) _Py_write_noraise(fd, str, (int)strlen(str))
+// Maximum string length (characters)
 #define MAX_STRING_LENGTH 500
+// Maximum number of frames per thread
 #define MAX_FRAME_DEPTH 100
+// Maximum number of threads
 #define MAX_NTHREADS 100
+// Maximum number of interpreters
+#define MAX_NINTERP 100
 
 /* Function from Parser/tokenizer.c */
 extern char* _PyTokenizer_FindEncodingFilename(int, PyObject *);
@@ -1252,13 +1257,16 @@ static void
 write_thread_id(int fd, PyThreadState *tstate, int is_current)
 {
     if (is_current)
-        PUTS(fd, "Current thread 0x");
+        PUTS(fd, "Current thread");
     else
-        PUTS(fd, "Thread 0x");
+        PUTS(fd, "Thread");
+    PUTS(fd, " #");
+    _Py_DumpDecimal(fd, tstate->id);
+    PUTS(fd, " (0x");
     _Py_DumpHexadecimal(fd,
                         tstate->thread_id,
                         sizeof(unsigned long) * 2);
-    PUTS(fd, " (most recent call first):\n");
+    PUTS(fd, ") (most recent call first):\n");
 }
 
 /* Dump the traceback of all Python threads into fd. Use write() to write the
@@ -1268,7 +1276,7 @@ write_thread_id(int fd, PyThreadState *tstate, int is_current)
    The caller is responsible to call PyErr_CheckSignals() to call Python signal
    handlers if signals were received. */
 const char*
-_Py_DumpTracebackThreads(int fd, PyInterpreterState *interp,
+_Py_DumpTracebackThreads(int fd, PyInterpreterState *current_interp,
                          PyThreadState *current_tstate)
 {
     PyThreadState *tstate;
@@ -1289,46 +1297,65 @@ _Py_DumpTracebackThreads(int fd, PyInterpreterState *interp,
         current_tstate = PyGILState_GetThisThreadState();
     }
 
-    if (interp == NULL) {
+    if (current_interp == NULL) {
         if (current_tstate == NULL) {
-            interp = _PyGILState_GetInterpreterStateUnsafe();
-            if (interp == NULL) {
-                /* We need the interpreter state to get Python threads */
-                return "unable to get the interpreter state";
-            }
+            current_interp = _PyGILState_GetInterpreterStateUnsafe();
         }
         else {
-            interp = current_tstate->interp;
+            current_interp = current_tstate->interp;
         }
     }
-    assert(interp != NULL);
-
-    /* Get the current interpreter from the current thread */
-    tstate = PyInterpreterState_ThreadHead(interp);
-    if (tstate == NULL)
-        return "unable to get the thread head state";
 
-    /* Dump the traceback of each thread */
-    tstate = PyInterpreterState_ThreadHead(interp);
-    nthreads = 0;
-    _Py_BEGIN_SUPPRESS_IPH
-    do
-    {
-        if (nthreads != 0)
+    _PyRuntimeState *runtime = &_PyRuntime;
+    PyInterpreterState *interp = runtime->interpreters.head;
+    int space = 0;
+    for (; interp != NULL; interp = interp->next) {
+        if (space) {
             PUTS(fd, "\n");
-        if (nthreads >= MAX_NTHREADS) {
-            PUTS(fd, "...\n");
-            break;
         }
-        write_thread_id(fd, tstate, tstate == current_tstate);
-        if (tstate == current_tstate && tstate->interp->gc.collecting) {
-            PUTS(fd, "  Garbage-collecting\n");
+        space = 1;
+
+        PUTS(fd, "=== ");
+        if (interp == current_interp) {
+            PUTS(fd, "Current interpreter");
         }
-        dump_traceback(fd, tstate, 0);
-        tstate = PyThreadState_Next(tstate);
-        nthreads++;
-    } while (tstate != NULL);
-    _Py_END_SUPPRESS_IPH
+        else {
+            PUTS(fd, "Interpreter");
+        }
+        PUTS(fd, " #");
+        _Py_DumpDecimal(fd, interp->id);
+
+        PUTS(fd, " (0x");
+        _Py_DumpHexadecimal(fd, (uintptr_t)interp, sizeof(uintptr_t) * 2);
+        PUTS(fd, ") ===\n\n");
+
+        /* Get the current interpreter from the current thread */
+        tstate = PyInterpreterState_ThreadHead(interp);
+        if (tstate == NULL)
+            return "unable to get the thread head state";
+
+        /* Dump the traceback of each thread */
+        tstate = PyInterpreterState_ThreadHead(interp);
+        nthreads = 0;
+        _Py_BEGIN_SUPPRESS_IPH
+        do
+        {
+            if (nthreads != 0)
+                PUTS(fd, "\n");
+            if (nthreads >= MAX_NTHREADS) {
+                PUTS(fd, "...\n");
+                break;
+            }
+            write_thread_id(fd, tstate, tstate == current_tstate);
+            if (tstate == current_tstate && tstate->interp->gc.collecting) {
+                PUTS(fd, "  Garbage-collecting\n");
+            }
+            dump_traceback(fd, tstate, 0);
+            tstate = PyThreadState_Next(tstate);
+            nthreads++;
+        } while (tstate != NULL);
+        _Py_END_SUPPRESS_IPH
+    }
 
     return NULL;
 }