diff --git a/acorn.js b/acorn.js
index c6341b605e..d4d7b87008 100644
--- a/acorn.js
+++ b/acorn.js
@@ -1245,15 +1245,15 @@
       } else if (ch === 92) { // "\"
         containsEsc = true;
         word += input.slice(chunkStart, tokPos);
+        var escStart = tokPos;
         if (input.charCodeAt(++tokPos) != 117) // "u"
           raise(tokPos, "Expecting Unicode escape sequence \\uXXXX");
         ++tokPos;
-        var esc = readHexChar(4);
-        var escStr = String.fromCharCode(esc);
-        if (!escStr) raise(tokPos - 1, "Invalid Unicode escape");
-        if (!(first ? isIdentifierStart(esc) : isIdentifierChar(esc)))
-          raise(tokPos - 4, "Invalid Unicode escape");
-        word += escStr;
+        var esc = readCodePoint();
+        if (esc.length != 1 ||
+            !(first ? isIdentifierStart : isIdentifierChar)(esc.charCodeAt(0)))
+          raise(escStart, "Invalid Unicode escape");
+        word += esc;
         chunkStart = tokPos;
       } else {
         break;
diff --git a/test/tests.js b/test/tests.js
index dfbfda0438..92f23f2ac4 100644
--- a/test/tests.js
+++ b/test/tests.js
@@ -26869,10 +26869,10 @@ testFail("x\\",
          "Expecting Unicode escape sequence \\uXXXX (1:2)");
 
 testFail("x\\u005c",
-         "Invalid Unicode escape (1:3)");
+         "Invalid Unicode escape (1:1)");
 
 testFail("x\\u002a",
-         "Invalid Unicode escape (1:3)");
+         "Invalid Unicode escape (1:1)");
 
 testFail("/",
          "Unterminated regular expression (1:1)");
@@ -27150,13 +27150,13 @@ testFail("\\\\",
          "Expecting Unicode escape sequence \\uXXXX (1:1)");
 
 testFail("\\u005c",
-         "Invalid Unicode escape (1:2)");
+         "Invalid Unicode escape (1:0)");
 
 testFail("\\x",
          "Expecting Unicode escape sequence \\uXXXX (1:1)");
 
 testFail("\\u0000",
-         "Invalid Unicode escape (1:2)");
+         "Invalid Unicode escape (1:0)");
 
 testFail("‌ = []",
          "Unexpected character '‌' (1:0)");