diff --git a/src/mips/simulator-mips.h b/src/mips/simulator-mips.h
index 69dddfa..1e72939 100644
--- a/src/mips/simulator-mips.h
+++ b/src/mips/simulator-mips.h
@@ -221,6 +221,10 @@
   // Pop an address from the JS stack.
   uintptr_t PopAddress();
 
+  // Debugger input.
+  void set_last_debugger_input(char* input);
+  char* last_debugger_input() { return last_debugger_input_; }
+
   // ICache checking.
   static void FlushICache(v8::internal::HashMap* i_cache, void* start,
                           size_t size);
@@ -305,6 +309,14 @@
   void InstructionDecode(Instruction* instr);
   // Execute one instruction placed in a branch delay slot.
   void BranchDelayInstructionDecode(Instruction* instr) {
+    if (instr->InstructionBits() == nopInstr) {
+      // Short-cut generic nop instructions. They are always valid and they
+      // never change the simulator state.
+      set_register(pc, reinterpret_cast<int32_t>(instr) +
+                       Instruction::kInstrSize);
+      return;
+    }
+
     if (instr->IsForbiddenInBranchDelay()) {
       V8_Fatal(__FILE__, __LINE__,
                "Eror:Unexpected %i opcode in a branch delay slot.",
@@ -358,6 +370,9 @@
   int icount_;
   int break_count_;
 
+  // Debugger input.
+  char* last_debugger_input_;
+
   // Icache simulation.
   v8::internal::HashMap* i_cache_;