diff --git a/lib/internal/assert/utils.js b/lib/internal/assert/utils.js
index 59b5a16f13..d059fa89ba 100644
--- a/lib/internal/assert/utils.js
+++ b/lib/internal/assert/utils.js
@@ -9,7 +9,6 @@ const {
   SafeMap,
   StringPrototypeCharCodeAt,
   StringPrototypeIncludes,
-  StringPrototypeIndexOf,
   StringPrototypeReplace,
   StringPrototypeSlice,
   StringPrototypeSplit,
@@ -174,7 +173,6 @@ function getErrMessage(message, fn) {
   const line = call.getLineNumber() - 1;
   let column = call.getColumnNumber() - 1;
   let identifier;
-  let code;
 
   if (filename) {
     identifier = `${filename}${line}${column}`;
@@ -199,31 +197,24 @@ function getErrMessage(message, fn) {
     // errors are handled faster.
     if (errorStackTraceLimitIsWritable) Error.stackTraceLimit = 0;
 
-    if (filename) {
-      if (decoder === undefined) {
-        const { StringDecoder } = require('string_decoder');
-        decoder = new StringDecoder('utf8');
-      }
-
-      // ESM file prop is a file proto. Convert that to path.
-      // This ensure opensync will not throw ENOENT for ESM files.
-      const fileProtoPrefix = 'file://';
-      if (StringPrototypeStartsWith(filename, fileProtoPrefix)) {
-        filename = fileURLToPath(filename);
-      }
-
-      fd = openSync(filename, 'r', 0o666);
-      // Reset column and message.
-      ({ 0: column, 1: message } = getCode(fd, line, column));
-      // Flush unfinished multi byte characters.
-      decoder.end();
-    } else {
-      for (let i = 0; i < line; i++) {
-        code = StringPrototypeSlice(code,
-                                    StringPrototypeIndexOf(code, '\n') + 1);
-      }
-      ({ 0: column, 1: message } = parseCode(code, column));
+    if (decoder === undefined) {
+      const { StringDecoder } = require('string_decoder');
+      decoder = new StringDecoder('utf8');
     }
+
+    // ESM file prop is a file proto. Convert that to path.
+    // This ensure opensync will not throw ENOENT for ESM files.
+    const fileProtoPrefix = 'file://';
+    if (StringPrototypeStartsWith(filename, fileProtoPrefix)) {
+      filename = fileURLToPath(filename);
+    }
+
+    fd = openSync(filename, 'r', 0o666);
+    // Reset column and message.
+    ({ 0: column, 1: message } = getCode(fd, line, column));
+    // Flush unfinished multi byte characters.
+    decoder.end();
+
     // Always normalize indentation, otherwise the message could look weird.
     if (StringPrototypeIncludes(message, '\n')) {
       if (EOL === '\r\n') {