diff --git a/src/validate_pyproject/api.py b/src/validate_pyproject/api.py
index 779daf6..2c6bce2 100644
--- a/src/validate_pyproject/api.py
+++ b/src/validate_pyproject/api.py
@@ -141,7 +141,8 @@ def _ensure_compatibility(self, reference: str, schema: Schema) -> Schema:
         if sid in self._schemas:
             raise errors.SchemaWithDuplicatedId(sid)
         version = schema.get("$schema")
-        if version and version != self.spec_version:
+        # Support schemas with missing trailing # (incorrect, but required before 0.15)
+        if version and version.rstrip("#") != self.spec_version.rstrip("#"):
             raise errors.InvalidSchemaVersion(reference, version, self.spec_version)
         return schema
 
diff --git a/src/validate_pyproject/plugins/distutils.schema.json b/src/validate_pyproject/plugins/distutils.schema.json
index 213fc0c..93cd2e8 100644
--- a/src/validate_pyproject/plugins/distutils.schema.json
+++ b/src/validate_pyproject/plugins/distutils.schema.json
@@ -1,5 +1,5 @@
 {
-  "$schema": "http://json-schema.org/draft-07/schema",
+  "$schema": "http://json-schema.org/draft-07/schema#",
 
   "$id": "https://setuptools.pypa.io/en/latest/deprecated/distutils/configfile.html",
   "title": "``tool.distutils`` table",
diff --git a/src/validate_pyproject/plugins/setuptools.schema.json b/src/validate_pyproject/plugins/setuptools.schema.json
index 8b31143..226facd 100644
--- a/src/validate_pyproject/plugins/setuptools.schema.json
+++ b/src/validate_pyproject/plugins/setuptools.schema.json
@@ -1,5 +1,5 @@
 {
-  "$schema": "http://json-schema.org/draft-07/schema",
+  "$schema": "http://json-schema.org/draft-07/schema#",
 
   "$id": "https://setuptools.pypa.io/en/latest/userguide/pyproject_config.html",
   "title": "``tool.setuptools`` table",
diff --git a/src/validate_pyproject/project_metadata.schema.json b/src/validate_pyproject/project_metadata.schema.json
index 462eb16..8ad7199 100644
--- a/src/validate_pyproject/project_metadata.schema.json
+++ b/src/validate_pyproject/project_metadata.schema.json
@@ -1,5 +1,5 @@
 {
-  "$schema": "http://json-schema.org/draft-07/schema",
+  "$schema": "http://json-schema.org/draft-07/schema#",
 
   "$id": "https://packaging.python.org/en/latest/specifications/declaring-project-metadata/",
   "title": "Package metadata stored in the ``project`` table",
diff --git a/src/validate_pyproject/pyproject_toml.schema.json b/src/validate_pyproject/pyproject_toml.schema.json
index 13a9105..2e06117 100644
--- a/src/validate_pyproject/pyproject_toml.schema.json
+++ b/src/validate_pyproject/pyproject_toml.schema.json
@@ -1,5 +1,5 @@
 {
-  "$schema": "http://json-schema.org/draft-07/schema",
+  "$schema": "http://json-schema.org/draft-07/schema#",
 
   "$id": "https://packaging.python.org/en/latest/specifications/declaring-build-dependencies/",
   "title": "Data structure for ``pyproject.toml`` files",
diff --git a/tests/test_api.py b/tests/test_api.py
index 4d5e75e..48e7ce2 100644
--- a/tests/test_api.py
+++ b/tests/test_api.py
@@ -41,14 +41,22 @@ def test_with_plugins(self):
         assert "setuptools" in tool["properties"]
         assert "$ref" in tool["properties"]["setuptools"]
 
-    def fake_plugin(self, name, schema_version=7):
+    def fake_plugin(self, name, schema_version=7, end="#"):
         schema = {
             "$id": f"https://example.com/{name}.schema.json",
-            "$schema": f"http://json-schema.org/draft-{schema_version:02d}/schema",
+            "$schema": f"http://json-schema.org/draft-{schema_version:02d}/schema{end}",
             "type": "object",
         }
         return types.Schema(schema)
 
+    @pytest.mark.parametrize("end", ["", "#"], ids=["no#", "with#"])
+    def test_schema_ending(self, end):
+        fn = wraps(self.fake_plugin)(partial(self.fake_plugin, end=end))
+        plg = plugins.PluginWrapper("plugin", fn)
+        registry = api.SchemaRegistry([plg])
+        main_schema = registry[registry.main]
+        assert main_schema["$schema"] == "http://json-schema.org/draft-07/schema#"
+
     def test_incompatible_versions(self):
         fn = wraps(self.fake_plugin)(partial(self.fake_plugin, schema_version=8))
         plg = plugins.PluginWrapper("plugin", fn)