diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index a76d63f..dd5c9cc 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -57,7 +57,7 @@ jobs:
           python -m build --sdist --outdir "$RUNNER_TEMP/varcode-dist"
           mkdir "$RUNNER_TEMP/varcode-sdist"
           tar -xzf "$RUNNER_TEMP"/varcode-dist/varcode-*.tar.gz --strip-components=1 -C "$RUNNER_TEMP/varcode-sdist"
-          # Osteosarc 0.14.x supports every Python version in this matrix;
+          # The supported Osteosarc range covers this Python matrix;
           # run native adapter checks against the bundled historical snapshot.
           python -m pip install "$RUNNER_TEMP/varcode-sdist[test-data]"
           python -m pip check
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7f84b10..69714d8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,11 @@
 # Change Log
 
+## [v10.11.10](https://github.com/openvax/varcode/tree/v10.11.10) (2026-10-08)
+
+- Allow osteosarc 0.15.x in the optional `test-data` extra and the snapshot
+  fixture's version check (`>=0.14.4,<0.16`), fixing five dataset tests that
+  errored during setup with osteosarc 0.15.5 (#581).
+
 ## [v10.11.9](https://github.com/openvax/varcode/tree/v10.11.9) (2026-10-06)
 
 - Require gtfparse 3.0.2+ across the supported Python/pandas matrix, coordinated
diff --git a/pyproject.toml b/pyproject.toml
index 12210b9..647af6d 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -35,7 +35,7 @@ include = ["varcode", "varcode.*"]
 
 [project.optional-dependencies]
 rna = ["pysam>=0.21"]
-test-data = ["osteosarc>=0.14.4,<0.15"]
+test-data = ["osteosarc>=0.14.4,<0.16"]
 
 [project.scripts]
 varcode-genes = "varcode.cli.genes_script:main"
diff --git a/tests/README.md b/tests/README.md
index f9b1003..06caf88 100644
--- a/tests/README.md
+++ b/tests/README.md
@@ -110,7 +110,7 @@ separate from export and tests.
 
 The targeted GPX4 and BRCA1 regressions use Ensembl 81. Offline integration
 checks use the public osteosarc dataset through the published
-osteosarc 0.14.x adapter (`>=0.14.4,<0.15`) from the optional `test-data` extra
+osteosarc 0.14.x/0.15.x adapter (`>=0.14.4,<0.16`) from the optional `test-data` extra
 (Python 3.9+):
 
 ```sh
@@ -141,7 +141,7 @@ To test an existing shared cache explicitly, set both
 identity must match. Missing packages, objects, or a mismatched snapshot then
 fail; the tests never fall back to the bundled snapshot. Without an explicit
 snapshot, these checks skip only when the optional Osteosarc dependency is
-absent. Osteosarc 0.7.x supports every Python version in the CI matrix.
+absent. The supported Osteosarc range covers every Python version in the CI matrix.
 
 These snapshot integration tests never download data or refresh sources. `Dataset.sync` acquires new
 snapshots separately; current remote sources do not reproduce the historical
diff --git a/tests/test_osteosarc_dataset.py b/tests/test_osteosarc_dataset.py
index 178a9c8..d6b9c65 100644
--- a/tests/test_osteosarc_dataset.py
+++ b/tests/test_osteosarc_dataset.py
@@ -44,7 +44,7 @@ def dataset(tmp_path_factory):
     from osteosarc import Cache, Dataset
 
     installed = tuple(int(part) for part in version("osteosarc").split(".")[:3])
-    assert (0, 14, 4) <= installed < (0, 15, 0)  # the test-data extra's range
+    assert (0, 14, 4) <= installed < (0, 16, 0)  # the test-data extra's range
     cache = Cache(cache_root, offline=True)
     data = Dataset.open(snapshot, cache=cache, offline=True)
     assert data.id == SNAPSHOT_ID
diff --git a/varcode/version.py b/varcode/version.py
index a65cffb..173644a 100644
--- a/varcode/version.py
+++ b/varcode/version.py
@@ -1 +1 @@
-__version__ = "10.11.9"
+__version__ = "10.11.10"