diff --git a/.github/workflows/staging-deploy.yml b/.github/workflows/staging-deploy.yml
index ba0fc04..e49c2cd 100644
--- a/.github/workflows/staging-deploy.yml
+++ b/.github/workflows/staging-deploy.yml
@@ -21,7 +21,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.8"]
+        python-version: ["3.12"]
     steps:
       - name: Checkout
         uses: actions/checkout@v4
diff --git a/app/Dockerfile b/app/Dockerfile
index 9f5ca25..f884b48 100755
--- a/app/Dockerfile
+++ b/app/Dockerfile
@@ -1,7 +1,7 @@
 # Base image that bundles AWS Lambda Python 3.8 image with some middleware functions
 # FROM base-eval-tmp
 # FROM rabidsheep55/python-base-eval-layer
-FROM ghcr.io/lambda-feedback/baseevalutionfunctionlayer:main-3.8
+FROM ghcr.io/lambda-feedback/baseevalutionfunctionlayer:main-3.12
 
 RUN yum install -y git
 
diff --git a/app/context/symbolic.py b/app/context/symbolic.py
index 77c41d9..6ba650a 100644
--- a/app/context/symbolic.py
+++ b/app/context/symbolic.py
@@ -1,5 +1,5 @@
 from copy import deepcopy
-from sympy import Add, Pow, Mul, Equality, pi, im, I, N
+from sympy import Add, Pow, Mul, Equality, pi, im, I, N, oo
 from sympy import re as real_part
 
 from ..utility.expression_utilities import (
@@ -83,6 +83,22 @@ def create_expressions_for_comparison(criterion, parameters_dict, local_substitu
     return lhs_expr, rhs_expr
 
 
+def do_comparison_infinite(comparison_symbol, lhs_expr, rhs_expr):
+    # When either side is infinite, subtracting (e.g. oo - oo) yields nan, making
+    # the subtraction-based do_comparison unreliable. Compare the sides directly instead.
+    direct_comparisons = {
+        "=": lhs_expr == rhs_expr,
+        ">": lhs_expr > rhs_expr,
+        ">=": lhs_expr >= rhs_expr,
+        "<": lhs_expr < rhs_expr,
+        "<=": lhs_expr <= rhs_expr,
+    }
+    try:
+        return bool(direct_comparisons[comparison_symbol.strip()])
+    except Exception:
+        return None
+
+
 def do_comparison(comparison_symbol, expression):
     comparisons = {
         "=": lambda expr: bool(expression.cancel().simplify().simplify() == 0),
@@ -106,7 +122,12 @@ def check_equality(criterion, parameters_dict, local_substitutions=[]):
     elif not isinstance(lhs_expr, Equality) and isinstance(rhs_expr, Equality):
         result = False
     else:
-        result = do_comparison(criterion.content, lhs_expr-rhs_expr)
+        # Subtraction of infinite values (e.g. oo - oo) yields nan rather than 0,
+        # so we use direct comparison when either side is infinite.
+        if lhs_expr.is_infinite or rhs_expr.is_infinite:
+            result = do_comparison_infinite(criterion.content, lhs_expr, rhs_expr)
+        else:
+            result = do_comparison(criterion.content, lhs_expr-rhs_expr)
         # There are some types of expression, e.g. those containing hyperbolic trigonometric functions, that can behave
         # unpredictably when simplification is applied. For that reason we check several different combinations of
         # simplifications here in order to reduce the likelihood of false negatives.
diff --git a/app/tests/symbolic_evaluation_test.py b/app/tests/symbolic_evaluation_test.py
index 607278c..56eda6f 100644
--- a/app/tests/symbolic_evaluation_test.py
+++ b/app/tests/symbolic_evaluation_test.py
@@ -784,10 +784,6 @@ def test_warning_inappropriate_symbol(self):
                 '(0,002*6800*v)/1,2',
                 '(0.002*6800*v)/1.2'
             ),
-            (
-                '-∞',
-                '-inf'
-            ),
             (
                 'x.y',
                 'x*y'
@@ -1936,6 +1932,11 @@ def test_unexpected_equalities_in_response_that_generates_set(self):
         result = evaluation_function(response, answer, params)
         assert result["is_correct"] is False
 
+    def test_infinity_unicode_symbol(self):
+        params = {'strict_syntax': True, 'elementary_functions': True}
+        result = evaluation_function('-∞', '-inf', params)
+        assert result["is_correct"] is True
+
     def test_infinity_alias(self):
         response = "2.694"
         answer = "infinity"
diff --git a/app/utility/expression_utilities.py b/app/utility/expression_utilities.py
index 57ca2b9..bc08b5e 100644
--- a/app/utility/expression_utilities.py
+++ b/app/utility/expression_utilities.py
@@ -62,7 +62,7 @@ def _print_log(self, expr, exp=None):
     ('acsch', ['arccsch', 'arccosech']), ('asech', ['arcsech']),
     ('exp', ['Exp']), ('E', ['e']), ('log', ['ln']),
     ('sqrt', []), ('sign', []), ('Abs', ['abs']), ('Max', ['max']), ('Min', ['min']), ('arg', []), ('ceiling', ['ceil']), ('floor', []),
-    ('oo',['Infinity', 'inf', 'infinity']),
+    ('oo',['Infinity', 'inf', 'infinity', '∞']),
     # Special symbols to make sure plus_minus and minus_plus are not destroyed during preprocessing
     ('plus_minus', []), ('minus_plus', []),
     # Below this line should probably not be collected with elementary functions. Some like 'common operations' would be a better name