diff --git a/.github/workflows/test-python.yml b/.github/workflows/test-python.yml
index e64fe689..0eeb35a0 100644
--- a/.github/workflows/test-python.yml
+++ b/.github/workflows/test-python.yml
@@ -47,7 +47,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           repository: 'mongodb-forks/django'
-          ref: 'mongodb-5.0.x'
+          ref: 'mongodb-5.1.x'
           path: 'django_repo'
       - name: Install system packages for Django's Python test dependencies
         run: |
diff --git a/django_mongodb/__init__.py b/django_mongodb/__init__.py
index a2dba98e..6ca36638 100644
--- a/django_mongodb/__init__.py
+++ b/django_mongodb/__init__.py
@@ -1,4 +1,4 @@
-__version__ = "5.0a0"
+__version__ = "5.1a0"
 
 # Check Django compatibility before other imports which may fail if the
 # wrong version of Django is installed.
diff --git a/django_mongodb/features.py b/django_mongodb/features.py
index c294027f..897ff611 100644
--- a/django_mongodb/features.py
+++ b/django_mongodb/features.py
@@ -99,7 +99,7 @@ class DatabaseFeatures(BaseDatabaseFeatures):
         "annotations.tests.NonAggregateAnnotationTestCase.test_mti_annotations",
         "expressions.test_queryset_values.ValuesExpressionsTests.test_values_list_expression",
         "expressions.test_queryset_values.ValuesExpressionsTests.test_values_list_expression_flat",
-        "expressions.tests.IterableLookupInnerExpressionsTests.test_expressions_in_lookups_join_choice",
+        "expressions.tests.IterableLookupInnerExpressionsTests.test_expressions_range_lookups_join_choice",
         "expressions_case.tests.CaseExpressionTests.test_join_promotion",
         "expressions_case.tests.CaseExpressionTests.test_join_promotion_multiple_annotations",
         "ordering.tests.OrderingTests.test_order_by_grandparent_fk_with_expression_in_default_ordering",
@@ -137,6 +137,8 @@ class DatabaseFeatures(BaseDatabaseFeatures):
         # QuerySet.explain() not implemented:
         # https://github.com/mongodb-labs/django-mongodb/issues/28
         "queries.test_explain.ExplainUnsupportedTests.test_message",
+        # $concat only supports strings, not int
+        "db_functions.text.test_concat.ConcatTests.test_concat_non_str",
     }
     # $bitAnd, #bitOr, and $bitXor are new in MongoDB 6.3.
     _django_test_expected_failures_bitwise = {
@@ -198,6 +200,8 @@ def django_test_expected_failures(self):
             "expressions.tests.BasicExpressionsTests.test_object_update_unsaved_objects",
             "expressions.tests.BasicExpressionsTests.test_order_of_operations",
             "expressions.tests.BasicExpressionsTests.test_parenthesis_priority",
+            "expressions.tests.BasicExpressionsTests.test_slicing_of_f_expressions_charfield",
+            "expressions.tests.BasicExpressionsTests.test_slicing_of_f_expressions_textfield",
             "expressions.tests.BasicExpressionsTests.test_update",
             "expressions.tests.BasicExpressionsTests.test_update_with_fk",
             "expressions.tests.BasicExpressionsTests.test_update_with_none",
@@ -320,6 +324,7 @@ def django_test_expected_failures(self):
             "expressions.tests.BasicExpressionsTests.test_boolean_expression_in_Q",
             "expressions.tests.BasicExpressionsTests.test_case_in_filter_if_boolean_output_field",
             "expressions.tests.BasicExpressionsTests.test_exists_in_filter",
+            "expressions.tests.BasicExpressionsTests.test_slicing_of_outerref",
             "expressions.tests.BasicExpressionsTests.test_subquery",
             "expressions.tests.ExistsTests.test_filter_by_empty_exists",
             "expressions.tests.ExistsTests.test_negated_empty_exists",
@@ -520,6 +525,7 @@ def django_test_expected_failures(self):
         "Test inspects query for SQL": {
             "delete.tests.DeletionTests.test_only_referenced_fields_selected",
             "lookup.tests.LookupTests.test_in_ignore_none",
+            "lookup.tests.LookupTests.test_lookup_direct_value_rhs_unwrapped",
             "lookup.tests.LookupTests.test_textfield_exact_null",
             "queries.tests.ExistsSql.test_exists",
             "queries.tests.Queries6Tests.test_col_alias_quoted",