diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 1caf110d19..8dd58a2ae6 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -3623,7 +3623,7 @@ void LCodeGen::DoBoundsCheck(LBoundsCheck* instr) {
   if (instr->length()->IsRegister()) {
     Register reg = ToRegister(instr->length());
     if (FLAG_debug_code &&
-        !instr->hydrogen()->index()->representation().IsTagged()) {
+        !instr->hydrogen()->length()->representation().IsTagged()) {
       __ AbortIfNotZeroExtended(reg);
     }
     if (instr->index()->IsConstantOperand()) {