diff --git a/src/crankshaft/hydrogen.cc b/src/crankshaft/hydrogen.cc
index a898c44574..36dce482bc 100644
--- a/src/crankshaft/hydrogen.cc
+++ b/src/crankshaft/hydrogen.cc
@@ -7508,6 +7508,12 @@ void HOptimizedGraphBuilder::BuildLoad(Property* expr,
     HValue* string = Pop();
     HInstruction* char_code = BuildStringCharCodeAt(string, index);
     AddInstruction(char_code);
+    if (char_code->IsConstant()) {
+      HConstant* c_code = HConstant::cast(char_code);
+      if (c_code->HasNumberValue() && std::isnan(c_code->DoubleValue())) {
+        Add<HDeoptimize>(DeoptimizeReason::kOutOfBounds, Deoptimizer::EAGER);
+      }
+    }
     instr = NewUncasted<HStringCharFromCode>(char_code);
 
   } else if (expr->key()->IsPropertyName()) {
diff --git a/test/mjsunit/regress/regress-crbug-665793.js b/test/mjsunit/regress/regress-crbug-665793.js
new file mode 100644
index 0000000000..d445d5194e
--- /dev/null
+++ b/test/mjsunit/regress/regress-crbug-665793.js
@@ -0,0 +1,12 @@
+// Copyright 2016 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax
+
+function foo() {
+  return 'x'[1];
+}
+assertEquals(undefined, foo());
+%OptimizeFunctionOnNextCall(foo);
+assertEquals(undefined, foo());