diff --git a/tasks.c b/tasks.c
index 013694dd34..f6af37bab8 100644
--- a/tasks.c
+++ b/tasks.c
@@ -3535,7 +3535,7 @@ static BaseType_t prvCreateIdleTasks( void )
     /* The length of the idle task name is limited to the minimum of the length
      * of configIDLE_TASK_NAME and configMAX_TASK_NAME_LEN - 2, keeping space
      * for the core ID suffix and the null-terminator. */
-    xIdleNameLen = sizeof( configIDLE_TASK_NAME ) - 1;
+    xIdleNameLen = strlen( configIDLE_TASK_NAME );
     xCopyLen = xIdleNameLen < ( configMAX_TASK_NAME_LEN - 2 ) ? xIdleNameLen : ( configMAX_TASK_NAME_LEN - 2 );
 
     for( xIdleTaskNameIndex = ( BaseType_t ) 0; xIdleTaskNameIndex < xCopyLen; xIdleTaskNameIndex++ )