diff --git a/include/timers.h b/include/timers.h
index f767d5c5a..a04f4841c 100644
--- a/include/timers.h
+++ b/include/timers.h
@@ -51,10 +51,16 @@
  * be used solely through the macros that make up the public software timer API,
  * as defined below.  The commands that are sent from interrupts must use the
  * highest numbers as tmrFIRST_FROM_ISR_COMMAND is used to determine if the task
- * or interrupt version of the queue send function should be used. */
+ * or interrupt version of the queue send function should be used.  Priority
+ * commands, which are sent to the front of the command queue, must begin at
+ * zero as tmrLAST_PRIORITY_COMMAND is used to determine if a command is a
+ * priority command. */
 #define tmrCOMMAND_EXECUTE_CALLBACK_FROM_ISR    ( ( BaseType_t ) -2 )
 #define tmrCOMMAND_EXECUTE_CALLBACK             ( ( BaseType_t ) -1 )
+
 #define tmrCOMMAND_START_DONT_TRACE             ( ( BaseType_t ) 0 )
+#define tmrLAST_PRIORITY_COMMAND                ( ( BaseType_t ) 0 )
+
 #define tmrCOMMAND_START                        ( ( BaseType_t ) 1 )
 #define tmrCOMMAND_RESET                        ( ( BaseType_t ) 2 )
 #define tmrCOMMAND_STOP                         ( ( BaseType_t ) 3 )
@@ -1316,7 +1322,7 @@ BaseType_t xTimerGenericCommand( TimerHandle_t xTimer,
                                  const BaseType_t xCommandID,
                                  const TickType_t xOptionalValue,
                                  BaseType_t * const pxHigherPriorityTaskWoken,
-                                 const TickType_t xTicksToWait ) PRIVILEGED_FUNCTION;
+                                 TickType_t xTicksToWait ) PRIVILEGED_FUNCTION;
 
 #if ( configUSE_TRACE_FACILITY == 1 )
     void vTimerSetTimerNumber( TimerHandle_t xTimer,
diff --git a/timers.c b/timers.c
index 07f3b3b3f..1345bbf84 100644
--- a/timers.c
+++ b/timers.c
@@ -375,13 +375,17 @@
                                      const BaseType_t xCommandID,
                                      const TickType_t xOptionalValue,
                                      BaseType_t * const pxHigherPriorityTaskWoken,
-                                     const TickType_t xTicksToWait )
+                                     TickType_t xTicksToWait )
     {
         BaseType_t xReturn = pdFAIL;
         DaemonTaskMessage_t xMessage;
 
         configASSERT( xTimer );
 
+        /* This function accepts only generic commands and not commands to execute
+         * a callback. */
+        configASSERT( xCommandID >= 0 );
+
         /* Send a message to the timer service task to perform a particular action
          * on a particular timer definition. */
         if( xTimerQueue != NULL )
@@ -393,24 +397,27 @@
 
             if( xCommandID < tmrFIRST_FROM_ISR_COMMAND )
             {
-                if( xTaskGetSchedulerState() == taskSCHEDULER_RUNNING )
+                /* The calls to xQueueSend below must not wait if the scheduler is
+                 * not running. */
+                if( xTaskGetSchedulerState() != taskSCHEDULER_RUNNING )
                 {
-                    /* The "start don't trace" command comes only from the timer
-                     * task itself. This command must be executed before any other
-                     * commands now in the queue for this timer, in case one of
-                     * those commands is stop or delete. */
-                    if( xCommandID == tmrCOMMAND_START_DONT_TRACE )
-                    {
-                        xReturn = xQueueSendToFront( xTimerQueue, &xMessage, xTicksToWait );
-                    }
-                    else
-                    {
-                        xReturn = xQueueSendToBack( xTimerQueue, &xMessage, xTicksToWait );
-                    }
+                    xTicksToWait = tmrNO_DELAY;
                 }
                 else
                 {
-                    xReturn = xQueueSendToBack( xTimerQueue, &xMessage, tmrNO_DELAY );
+                    mtCOVERAGE_TEST_MARKER();
+                }
+
+                /* Priority commands must be executed before any standard commands
+                 * now in the queue for this timer, so them to the front of the
+                 * queue. */
+                if( xCommandID <= tmrLAST_PRIORITY_COMMAND )
+                {
+                    xReturn = xQueueSendToFront( xTimerQueue, &xMessage, xTicksToWait );
+                }
+                else
+                {
+                    xReturn = xQueueSendToBack( xTimerQueue, &xMessage, xTicksToWait );
                 }
             }
             else