diff --git a/dbus/dbus-gmain.c b/dbus/dbus-gmain.c
index 7496c65..300c5a2 100644
--- a/dbus/dbus-gmain.c
+++ b/dbus/dbus-gmain.c
@@ -238,6 +238,9 @@ io_handler_dispatch (GIOChannel   *source,
   return TRUE;
 }
 
+/* Attach the connection setup to the given watch, removing any
+ * previously-attached connection setup.
+ */
 static void
 connection_setup_add_watch (ConnectionSetup *cs,
                             DBusWatch       *watch)
@@ -250,8 +253,6 @@ connection_setup_add_watch (ConnectionSetup *cs,
   if (!dbus_watch_get_enabled (watch))
     return;
   
-  g_assert (dbus_watch_get_data (watch) == NULL);
-  
   flags = dbus_watch_get_flags (watch);
 
   condition = G_IO_ERR | G_IO_HUP;
@@ -285,7 +286,7 @@ connection_setup_remove_watch (ConnectionSetup *cs,
 
   handler = dbus_watch_get_data (watch);
 
-  if (handler == NULL)
+  if (handler == NULL || handler->cs != cs)
     return;
   
   io_handler_destroy_source (handler);
diff --git a/test/core/30574.c b/test/core/30574.c
new file mode 100644
index 0000000..51eaf30
--- /dev/null
+++ b/test/core/30574.c
@@ -0,0 +1,94 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "dbus/dbus.h"
+#include "glib.h"
+
+DBusConnection *bus;
+GMainContext *main_context;
+
+typedef struct _SpiReentrantCallClosure 
+{
+  GMainLoop   *loop;
+  DBusMessage *reply;
+} SpiReentrantCallClosure;
+
+static void
+set_reply (DBusPendingCall * pending, void *user_data)
+{
+  SpiReentrantCallClosure* closure = (SpiReentrantCallClosure *) user_data; 
+
+  closure->reply = dbus_pending_call_steal_reply (pending);
+  dbus_connection_setup_with_g_main (bus, NULL);
+
+  g_main_loop_quit (closure->loop);
+}
+
+static DBusMessage *
+send_and_allow_reentry (DBusConnection * bus, DBusMessage * message)
+{
+  DBusPendingCall *pending;
+  SpiReentrantCallClosure closure;
+
+  closure.loop = g_main_loop_new (main_context, FALSE);
+  dbus_connection_setup_with_g_main (bus, main_context);
+
+  if (!dbus_connection_send_with_reply (bus, message, &pending, 3000))
+    {
+  dbus_connection_setup_with_g_main (bus, NULL);
+      return NULL;
+    }
+  dbus_pending_call_set_notify (pending, set_reply, (void *) &closure, NULL);
+  g_main_loop_run  (closure.loop);
+  
+  g_main_loop_unref (closure.loop);
+  return closure.reply;
+}
+
+main(int argc, const char *argv[])
+{
+  DBusError error;
+  DBusMessage *message = NULL, *reply = NULL;
+  dbus_int32_t pid;
+  const char *str;
+
+  main_context = g_main_context_new ();
+  dbus_error_init (&error);
+  bus = dbus_bus_get (DBUS_BUS_SESSION, &error);
+  if (!bus)
+  {
+    fprintf(stderr, "Couldn't connect to bus: %s\n", error.name);
+    return 1;
+  }
+  dbus_connection_setup_with_g_main (bus, NULL);
+  message = dbus_message_new_method_call ("org.freedesktop.DBus", "/org/freedesktop/DBus", DBUS_INTERFACE_DBUS, "GetId");
+  reply = send_and_allow_reentry (bus, message);
+  if (dbus_message_get_type (reply) == DBUS_MESSAGE_TYPE_ERROR)
+  {
+    char *err;
+    dbus_message_get_args (reply, NULL, DBUS_TYPE_STRING, &err, DBUS_TYPE_INVALID);
+    fprintf (stderr, "Got error: %s\n", err);
+    return 1;
+  }
+  dbus_message_unref (reply);
+  dbus_message_unref (message);
+  message = dbus_message_new_method_call ("org.freedesktop.DBus", "/org/freedesktop/DBus", DBUS_INTERFACE_DBUS, "GetId");
+  reply = send_and_allow_reentry (bus, message);
+  if (!reply)
+  {
+    fprintf(stderr, "Sorry; dbus wouldn't answer me: %s\n", error.message);
+    exit(1);
+  }
+  if (dbus_message_get_type (reply) == DBUS_MESSAGE_TYPE_ERROR)
+  {
+    char *err;
+    dbus_message_get_args (reply, NULL, DBUS_TYPE_STRING, &err, DBUS_TYPE_INVALID);
+    fprintf (stderr, "Got error: %s\n", err);
+    return 1;
+  }
+  if (!dbus_message_get_args (reply, &error, DBUS_TYPE_STRING, &str, DBUS_TYPE_INVALID))
+  {
+    fprintf(stderr, "Sorry; can't communicate: %s\n", error.message);
+    exit(1);
+  }
+  exit (0);
+}
diff --git a/test/core/Makefile.am b/test/core/Makefile.am
index 404a490..ccb17f6 100644
--- a/test/core/Makefile.am
+++ b/test/core/Makefile.am
@@ -54,6 +54,7 @@ noinst_PROGRAMS = \
 	peer-client \
 	test-types \
 	test-5688 \
+	test-30574 \
 	test-unregister \
 	test-variant-recursion \
 	test-gvariant
@@ -66,6 +67,9 @@ test_5688_SOURCES = \
 	my-object-marshal.c \
 	5688.c
 
+test_30574_SOURCES = \
+	30574.c
+
 test_unregister_SOURCES = \
 	my-object.c \
 	my-object.h \
diff --git a/test/core/run-test.sh b/test/core/run-test.sh
index 5d32d95..0351472 100755
--- a/test/core/run-test.sh
+++ b/test/core/run-test.sh
@@ -49,4 +49,5 @@ else
   ${DBUS_TOP_BUILDDIR}/libtool --mode=execute $DEBUG $DBUS_TOP_BUILDDIR/test/core/test-dbus-glib || die "test-dbus-glib failed"
   ${DBUS_TOP_BUILDDIR}/libtool --mode=execute $DEBUG $DBUS_TOP_BUILDDIR/test/core/test-variant-recursion || die "test-variant-recursion failed"
   ${DBUS_TOP_BUILDDIR}/libtool --mode=execute $DEBUG $DBUS_TOP_BUILDDIR/test/core/test-gvariant || die "test-gvariant failed"
+  ${DBUS_TOP_BUILDDIR}/libtool --mode=execute $DEBUG $DBUS_TOP_BUILDDIR/test/core/test-30574 || die "test-30574 failed"
 fi