diff --git a/firmware/thread.c b/firmware/thread.c
index a46351cb1f..2651a4f2d7 100644
--- a/firmware/thread.c
+++ b/firmware/thread.c
@@ -31,7 +31,7 @@ struct regs
 
 int num_threads;
 static int current_thread;
-static struct regs thread_contexts[MAXTHREADS];
+static struct regs thread_contexts[MAXTHREADS] __attribute__ ((section(".idata")));
 char *thread_name[MAXTHREADS];
 void *thread_stack[MAXTHREADS];
 int thread_stack_size[MAXTHREADS];
@@ -40,6 +40,8 @@ static char main_thread_name[] = "main";
 extern int stackbegin[];
 extern int stackend[];
 
+void switch_thread(void) __attribute__ ((section(".icode")));
+
 /*--------------------------------------------------------------------------- 
  * Store non-volatile context.
  *---------------------------------------------------------------------------