diff --git a/lib/init/eval.js b/lib/init/eval.js
index fe19a0c1..41bca44b 100644
--- a/lib/init/eval.js
+++ b/lib/init/eval.js
@@ -194,6 +194,7 @@ function execEvalCode(exec, arg, shouldThrowSyntaxError, code, fn) {
  *   {string} .code - Instrumented code (or input code if parsing failed)
  *   {boolean} .shouldThrow - `true` if could not parse code, so calling `eval()` with this code
  *     should throw syntax error
+ *   {boolean} .prefixNumChanged - `true` if prefix num inside `eval()` differs from outside
  */
 function compile(code, tracker, filename, isIndirectEval, state, isStrict) {
 	// Parse code.
@@ -205,7 +206,7 @@ function compile(code, tracker, filename, isIndirectEval, state, isStrict) {
 			code, filename, false, false, !isIndirectEval, false, isStrict, false, undefined
 		).ast;
 	} catch (err) {
-		return {code, shouldThrow: true};
+		return {code, shouldThrow: true, prefixNumChanged: false};
 	}
 
 	// Instrument code.