diff --git a/arch/msp430/common/include/tos_cpu.h b/arch/msp430/common/include/tos_cpu.h
index 3aef5447..c85ce18c 100644
--- a/arch/msp430/common/include/tos_cpu.h
+++ b/arch/msp430/common/include/tos_cpu.h
@@ -3,7 +3,7 @@
 
 typedef struct cpu_context_st {
     cpu_data_t      _R0; //PC
-    cpu_data_t      _R1; //SP
+    //cpu_data_t      _R1; //SP
     cpu_data_t      _R2; //SR
     //cpu_data_t      _R3; 
     cpu_data_t      _R4;