diff --git a/pyproject.toml b/pyproject.toml
index db1fa8161..e3adf16a1 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -82,11 +82,11 @@ dependencies = [
     "sympy",
     "astropy",
     "toml",
-    # 26.7.25 bounds the time a fetch can take: every request carries an
+    # This floor bounds the time a fetch can take: every request carries an
     # explicit connect and read timeout, and a transient failure is retried
     # with backoff instead of ending the fetch. Below that floor a stalled
     # mirror hangs the start of a run with no diagnostic.
-    "fwl-io>=26.7.25",
+    "fwl-io>=26.8.31",
     "zenodo-get",
     "zenodo-client>=0.4.1",
     "osfclient",
diff --git a/src/proteus/data/__init__.py b/src/proteus/data/__init__.py
index 83e06a9e3..a4716181c 100644
--- a/src/proteus/data/__init__.py
+++ b/src/proteus/data/__init__.py
@@ -24,10 +24,10 @@
 EXOPLANET_REFERENCE = 'observe.exoplanet_reference'
 MASS_RADIUS_ZENG_2019 = 'observe.mass_radius.zeng_2019'
 
-# The manifest schema this manifest is written against. An fwl-io older than
-# this reads the manifest as malformed rather than as a version mismatch, so the
-# load names which side is out of date. Keep in step with the fwl-io requirement
-# in pyproject.toml; the test suite pins the two together.
+# The oldest fwl-io that reads this manifest schema. An older fwl-io reads the
+# manifest as malformed rather than as a version mismatch, so the load names
+# which side is out of date. The fwl-io requirement in pyproject.toml must be at
+# least this version; the test suite enforces the relation.
 FWL_IO_FLOOR = '26.7.25'
 
 
diff --git a/tests/data/test_manifest.py b/tests/data/test_manifest.py
index c966572b1..32207c602 100644
--- a/tests/data/test_manifest.py
+++ b/tests/data/test_manifest.py
@@ -238,13 +238,16 @@ class _NewDataset:
     assert _fwl_io_derives_the_location() is True
 
 
-def test_declared_floor_matches_the_requirement():
-    """The fwl-io floor in the error message equals the one pip installs.
+def test_declared_floor_is_not_below_the_schema_floor():
+    """The pyproject fwl-io floor is not below the manifest schema floor.
 
-    If the two drift, the upgrade instruction names a version that does not fix
-    the problem the reader is looking at.
+    A pyproject floor below the schema floor would let pip install an fwl-io that
+    cannot read the manifest, which the load reports as a stale install. A
+    pyproject floor above it is allowed: it tracks fixes in later fwl-io
+    releases, and the upgrade instruction names only the schema floor.
     """
     from packaging.requirements import Requirement
+    from packaging.version import Version
 
     requirements = _pyproject()['project']['dependencies']
     bounds = [
@@ -258,7 +261,9 @@ def test_declared_floor_matches_the_requirement():
     # Checked first so a dropped `>=` reports the absence it is, rather than
     # reaching the comparison below and reading as a version mismatch.
     assert len(bounds) == 1, f'expected one lower bound on fwl-io, found {bounds}'
-    assert bounds == [FWL_IO_FLOOR], f'pyproject floor {bounds} vs module floor {FWL_IO_FLOOR}'
+    assert Version(bounds[0]) >= Version(FWL_IO_FLOOR), (
+        f'pyproject floor {bounds[0]} is below the manifest schema floor {FWL_IO_FLOOR}'
+    )
 
 
 def test_manifest_and_registries_are_declared_as_package_data():