diff --git a/parser/astgen/eval_literal.py b/parser/astgen/eval_literal.py
index a2ae949..8d3b419 100644
--- a/parser/astgen/eval_literal.py
+++ b/parser/astgen/eval_literal.py
@@ -64,13 +64,12 @@ def _handle_hex_escape(self, length, i, start_i):
             raise self.err(
                 f"Unterminated escape in string (expected {length}"
                 f" hex digits)", StrRegion(start_i, i))
-        try:
-            value = int(digits, base=16)
-        except ValueError:
+        if set(digits) - _HEX_DIGITS:
             # Just report entire escape as error region
             raise self.err(
                 f"Invalid escape in string (expected {length} hex digits)",
-                StrRegion(start_i, i)) from None
+                StrRegion(start_i, i))
+        value = int(digits, base=16)  # Should never be error here (only hex digits here)
         return chr(value), i
 
     # the Very Special Case: \N{......}
@@ -129,3 +128,4 @@ def err(self, msg: str, subregion: StrRegion):
     'u': 4,  # \uHHHH
     'U': 8,  # \Uhhhhhhhh
 }
+_HEX_DIGITS = set('0123456789abcdef')
diff --git a/test/coverage/inject_me.js b/test/coverage/inject_me.js
index 5d22260..b810848 100644
--- a/test/coverage/inject_me.js
+++ b/test/coverage/inject_me.js
@@ -36,9 +36,28 @@ function linkifyRow(tr) {
 function linkifyAll() {
   document.querySelectorAll('tr.region').forEach(linkifyRow);
 }
+const PREVENT_FILTER_TOTAL = true;
+function preventUpdateTotalCell(cell) {
+  let target = cell.classList;
+  let oldContains = target.contains.bind(target);
+  function newContains(value) {
+    // Tell the Coverage.py code that all entries in total row are 'name'
+    // so it doesn't try to modify them.
+    if (value == "name") return true;
+    return oldContains(value);
+  }
+  target.contains = newContains;
+}
+function preventUpdateTotal() {
+  [...document.querySelector('table.index').tFoot.rows[0].cells]
+    .forEach(preventUpdateTotalCell);
+}
 addEventListener('load', () => {
   if(document.body.classList.contains("indexfile")) {
     setColors();
     linkifyAll();
+    if(PREVENT_FILTER_TOTAL) {
+      preventUpdateTotal();
+    }
   }
 });
diff --git a/test/test_eval_literal.py b/test/test_eval_literal.py
index 625e6a4..5ff0d25 100644
--- a/test/test_eval_literal.py
+++ b/test/test_eval_literal.py
@@ -69,6 +69,13 @@ def test_error(self):
             r'tests would break}"', StrRegion(3, 3 + 73))
         self.assertContains(msg.lower(), "unknown unicode character name")
 
+    def test_bad_hex_escape_2(self):
+        msg = self._assert_err_and_region(r'"\x-9"', StrRegion(3, 7))
+        self.assertContains(msg, "expected 2")
+
+        msg = self._assert_err_and_region(r'"\u 4fe1"', StrRegion(3, 9))
+        self.assertContains(msg, "expected 4")
+
     def test_py_consistency(self):
         base = r'a\\\a\b\v\f\0\n\rq\t' '\\"' "\\'"
         for x in (*range(0, 34, 3), *range(34, 256, 9), 255):