diff --git a/browsergym/assistantbench/src/browsergym/assistantbench/evaluation/evaluate_utils/evaluate_dicts.py b/browsergym/assistantbench/src/browsergym/assistantbench/evaluation/evaluate_utils/evaluate_dicts.py
index 76136c06a..b5778dc11 100644
--- a/browsergym/assistantbench/src/browsergym/assistantbench/evaluation/evaluate_utils/evaluate_dicts.py
+++ b/browsergym/assistantbench/src/browsergym/assistantbench/evaluation/evaluate_utils/evaluate_dicts.py
@@ -2,7 +2,7 @@
 
 import numpy as np
 
-from .utils import _align_bags
+from .utils import _align_bags, _fix_comma
 
 
 def calculate_f1_score(precision, recall):
@@ -43,7 +43,7 @@ def fix_number(number):
             " ".join(" ".join(copy_ans.split("$")).split("%")).split("sqft")
         ).strip()
         copy_ans = copy_ans.strip()
-        copy_ans = copy_ans.replace(",", ".")
+        copy_ans = _fix_comma(copy_ans)
         try:
             return float(copy_ans)
         except:
diff --git a/browsergym/assistantbench/src/browsergym/assistantbench/evaluation/evaluate_utils/utils.py b/browsergym/assistantbench/src/browsergym/assistantbench/evaluation/evaluate_utils/utils.py
index 82be9e4ad..dec157701 100644
--- a/browsergym/assistantbench/src/browsergym/assistantbench/evaluation/evaluate_utils/utils.py
+++ b/browsergym/assistantbench/src/browsergym/assistantbench/evaluation/evaluate_utils/utils.py
@@ -1,3 +1,4 @@
+import re
 from typing import Callable, List, Set
 
 import numpy as np
@@ -23,3 +24,23 @@ def _align_bags(
     for row, column in zip(row_ind, col_ind):
         max_scores[row] = max(max_scores[row], scores[row, column])
     return max_scores
+
+
+def _fix_comma(number: str) -> str:
+    """
+    Distinguishes US thousands separators from European decimal commas.
+
+    Multiple commas, or a single comma followed by exactly 3 digits, are
+    treated as thousands separators and removed; a single comma followed by
+    1 or 2 digits is treated as a decimal comma and replaced by a period.
+    Anything else is left untouched.
+    """
+    if number.count(",") > 1:
+        return number.replace(",", "")
+    match = re.fullmatch(r"(-?\d+),(\d+)", number)
+    if match:
+        if len(match.group(2)) == 3:
+            return number.replace(",", "")
+        if len(match.group(2)) <= 2:
+            return number.replace(",", ".")
+    return number
diff --git a/browsergym/assistantbench/src/browsergym/assistantbench/evaluation/evaluator.py b/browsergym/assistantbench/src/browsergym/assistantbench/evaluation/evaluator.py
index 7910eadf8..3eb1e1dd9 100644
--- a/browsergym/assistantbench/src/browsergym/assistantbench/evaluation/evaluator.py
+++ b/browsergym/assistantbench/src/browsergym/assistantbench/evaluation/evaluator.py
@@ -5,6 +5,7 @@
 import numpy as np
 
 from .evaluate_utils.evaluate_factory import get_evaluator
+from .evaluate_utils.utils import _fix_comma
 
 
 def find_isnan(samp):
@@ -60,7 +61,8 @@ def fix_number(number):
             " ".join(" ".join(copy_ans.split("$")).split("%")).split("sqft")
         ).strip()
         copy_ans = copy_ans.strip()
-        copy_ans = copy_ans.replace(",", ".").replace(" square kilometers", "")
+        copy_ans = copy_ans.replace(" square kilometers", "")
+        copy_ans = _fix_comma(copy_ans)
         try:
             return float(copy_ans), True
         except:
diff --git a/tests/assistantbench/test_evaluation.py b/tests/assistantbench/test_evaluation.py
index 4973d7158..cb3a829b8 100644
--- a/tests/assistantbench/test_evaluation.py
+++ b/tests/assistantbench/test_evaluation.py
@@ -52,6 +52,36 @@ def test_evaluate(original_id: str):
     assert has_ans == expected_has_ans
 
 
+@pytest.mark.parametrize(
+    "prediction, gold_answer, expected_score",
+    [
+        # US thousands separators must be removed before parsing (#404)
+        ("3,080,000", "3080000", 1.0),
+        ("1,000", "1000", 1.0),
+        # European decimal commas must keep scoring 1.0
+        ("14,2", "14.2", 1.0),
+        # 1000x errors must no longer score 1.0 (#404)
+        ("1,000", "1", 0.0),
+        ("1,010", "1.01", 0.0),
+    ],
+)
+def test_evaluate_comma_numbers(prediction, gold_answer, expected_score):
+
+    score, _ = question_scorer(prediction, gold_answer)
+
+    assert score == expected_score
+
+
+def test_evaluate_comma_numbers_in_dicts():
+
+    prediction = '[{"sender": "DHL", "price": "1,000"}]'
+    gold_answer = '{"sender": "DHL", "price": 1000}'
+
+    score, _ = question_scorer(prediction, gold_answer)
+
+    assert score == 1.0
+
+
 @pytest.mark.parametrize(
     "original_id",
     [id for id in data_points.keys() if isinstance(data_points[id]["answer"], (str, float, int))],