diff --git a/kernel/atomtimer.c b/kernel/atomtimer.c
index 9bb123b..ea8208a 100755
--- a/kernel/atomtimer.c
+++ b/kernel/atomtimer.c
@@ -488,7 +488,12 @@ static void atomTimerCallbacks (void)
         next_ptr = callback_list_head;
         while (next_ptr)
         {
+            /*
+             *  Save the next timer in the list (in case the callback
+             *  modifies the list by registering again.
+             */
             saved_next_ptr = next_ptr->next_timer;
+
             /* Call the registered callback */
             if (next_ptr->cb_func)
             {
diff --git a/tests/timer8.c b/tests/timer8.c
new file mode 100644
index 0000000..4f5a07f
--- /dev/null
+++ b/tests/timer8.c
@@ -0,0 +1,140 @@
+/*
+ * Copyright (c) 2016, Kelvin Lawson. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. No personal names or organizations' names associated with the
+ *    Atomthreads project may be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE ATOMTHREADS PROJECT AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+
+#include "atom.h"
+#include "atomtimer.h"
+#include "atomtests.h"
+
+
+/* Tick delay before each callback */
+#define CALLBACK_TICKS			2
+
+/* Number of re-registrations to make from callbacks */
+#define NUM_CALLBACKS 			(SYSTEM_TICKS_PER_SEC / CALLBACK_TICKS)
+
+
+/* Test OS objects */
+static ATOM_TIMER timer_cb;
+
+
+/* Global test data */
+static int callback_ran_count;
+
+
+/* Forward declarations */
+static void testCallback (POINTER cb_data);
+
+
+/**
+ * \b test_start
+ *
+ * Start timer test.
+ *
+ * This test checks that a timer can be registered from within a timer
+ * callback context. i.e. checks the kernel timer queue can handle additions
+ * to the timer queue while already walking the queue during a timer callback.
+ *
+ * @retval Number of failures
+ */
+uint32_t test_start (void)
+{
+    int failures;
+
+    /* Default to zero failures */
+    failures = 0;
+
+    /* Clear down the callback count */
+    callback_ran_count = 0;
+
+    /* Fill out timer request structures for 2 ticks from now */
+    timer_cb.cb_ticks = CALLBACK_TICKS;
+    timer_cb.cb_func = testCallback;
+    timer_cb.cb_data = &callback_ran_count;
+
+    /* Register timer */
+    if (atomTimerRegister (&timer_cb) != ATOM_OK)
+    {
+        ATOMLOG (_STR("TimerReg\n"));
+        failures++;
+    }
+
+    /* Timer was successfully created */
+    else
+    {
+        /* Sleep for twice the period we expect the test to take */
+        atomTimerDelay (2 * CALLBACK_TICKS * NUM_CALLBACKS);
+
+        /*
+        * We should now find that the timer callback has run the correct
+        * number of times.
+        */
+        if (callback_ran_count != NUM_CALLBACKS)
+        {
+            ATOMLOG (_STR("Callback count %d vs %d\n"), callback_ran_count, NUM_CALLBACKS);
+            failures++;
+        }
+    }
+
+    /* Quit */
+    return failures;
+
+}
+
+
+/**
+ * \b testCallback
+ *
+ * Increment a counut to say we ran. Also register the same timer to occur
+ * again, up to a fixed number of times. The main test procedure can wait
+ * and check the count to see that all of the requested callbacks occurred
+ * (and hence timer registration from within a timer callback worked).
+ *
+ * @param[in] cb_data Pointer to counter of callback runs
+ */
+static void testCallback (POINTER cb_data)
+{
+    int *ran_count_ptr = (int *)cb_data;
+
+    /* Callback was called */
+    *ran_count_ptr += 1;
+
+    /* If the test is still running, register the same timer again */
+    if (*ran_count_ptr < NUM_CALLBACKS)
+    {
+        /*  Same timer details as previously */
+        timer_cb.cb_ticks = CALLBACK_TICKS;
+        timer_cb.cb_func = testCallback;
+        timer_cb.cb_data = &callback_ran_count;
+        if (atomTimerRegister (&timer_cb) != ATOM_OK)
+        {
+            ATOMLOG (_STR("TimerCbReg\n"));
+        }
+    }
+}