diff --git a/CHANGES.md b/CHANGES.md
index 940b7b84..abff6ce4 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -4,8 +4,10 @@
 
 ### Changed
 
-* switch from `fastapi` to `fastapi-slim` to avoid installing unwanted dependencies. ([#687](https://github.com/stac-utils/stac-fastapi/pull/687))
-* replace Enum with `Literal` for `FilterLang`. ([#686](https://github.com/stac-utils/stac-fastapi/pull/686))
+* Switch from `fastapi` to `fastapi-slim` to avoid installing unwanted dependencies. ([#687](https://github.com/stac-utils/stac-fastapi/pull/687))
+* Replace Enum with `Literal` for `FilterLang`. ([#686](https://github.com/stac-utils/stac-fastapi/pull/686))
+* Update stac-pydantic requirement to `~3.1` ([#697](https://github.com/stac-utils/stac-fastapi/pull/697))
+* Fix datetime interval for GET Search when passing a single value ([#697](https://github.com/stac-utils/stac-fastapi/pull/697))
 
 ### Removed
 
diff --git a/stac_fastapi/api/stac_fastapi/api/app.py b/stac_fastapi/api/stac_fastapi/api/app.py
index ed9a1cc7..7eb7c4e8 100644
--- a/stac_fastapi/api/stac_fastapi/api/app.py
+++ b/stac_fastapi/api/stac_fastapi/api/app.py
@@ -172,14 +172,14 @@ def register_conformance_classes(self):
             name="Conformance Classes",
             path="/conformance",
             response_model=(
-                api.ConformanceClasses if self.settings.enable_response_models else None
+                api.Conformance if self.settings.enable_response_models else None
             ),
             responses={
                 200: {
                     "content": {
                         MimeTypes.json.value: {},
                     },
-                    "model": api.ConformanceClasses,
+                    "model": api.Conformance,
                 },
             },
             response_class=self.response_class,
diff --git a/stac_fastapi/api/tests/benchmarks.py b/stac_fastapi/api/tests/benchmarks.py
index 95e1c532..475250d7 100644
--- a/stac_fastapi/api/tests/benchmarks.py
+++ b/stac_fastapi/api/tests/benchmarks.py
@@ -17,6 +17,7 @@
 collections = [
     stac_types.Collection(
         id=f"test_collection_{n}",
+        type="Collection",
         title="Test Collection",
         description="A test collection",
         keywords=["test"],
@@ -25,7 +26,7 @@
             "spatial": {"bbox": [[-180, -90, 180, 90]]},
             "temporal": {"interval": [["2000-01-01T00:00:00Z", None]]},
         },
-        links=collection_links.dict(exclude_none=True),
+        links=collection_links.model_dump(exclude_none=True),
     )
     for n in range(0, 10)
 ]
@@ -37,7 +38,7 @@
         geometry={"type": "Point", "coordinates": [0, 0]},
         bbox=[-180, -90, 180, 90],
         properties={"datetime": "2000-01-01T00:00:00Z"},
-        links=item_links.dict(exclude_none=True),
+        links=item_links.model_dump(exclude_none=True),
         assets={},
     )
     for n in range(0, 1000)
diff --git a/stac_fastapi/api/tests/conftest.py b/stac_fastapi/api/tests/conftest.py
index 1b89f07c..33919e83 100644
--- a/stac_fastapi/api/tests/conftest.py
+++ b/stac_fastapi/api/tests/conftest.py
@@ -16,6 +16,7 @@
 @pytest.fixture
 def _collection():
     return Collection(
+        type="Collection",
         id="test_collection",
         title="Test Collection",
         description="A test collection",
diff --git a/stac_fastapi/types/setup.py b/stac_fastapi/types/setup.py
index 0dd166ec..c8f2f9df 100644
--- a/stac_fastapi/types/setup.py
+++ b/stac_fastapi/types/setup.py
@@ -9,7 +9,7 @@
     "fastapi-slim",
     "attrs>=23.2.0",
     "pydantic-settings>=2",
-    "stac_pydantic>=3",
+    "stac_pydantic~=3.1",
     "iso8601>=1.0.2,<2.2.0",
 ]
 
diff --git a/stac_fastapi/types/stac_fastapi/types/core.py b/stac_fastapi/types/stac_fastapi/types/core.py
index fdf020b0..ba6ebe44 100644
--- a/stac_fastapi/types/stac_fastapi/types/core.py
+++ b/stac_fastapi/types/stac_fastapi/types/core.py
@@ -380,10 +380,8 @@ def landing_page(self, **kwargs) -> stac.LandingPage:
         if self.extension_is_enabled("FilterExtension"):
             landing_page["links"].append(
                 {
-                    # TODO: replace this with Relations.queryables.value,
-                    "rel": "http://www.opengis.net/def/rel/ogc/1.0/queryables",
-                    # TODO: replace this with MimeTypes.jsonschema,
-                    "type": "application/schema+json",
+                    "rel": Relations.queryables.value,
+                    "type": MimeTypes.jsonschema.value,
                     "title": "Queryables",
                     "href": urljoin(base_url, "queryables"),
                     "method": "GET",
@@ -586,10 +584,8 @@ async def landing_page(self, **kwargs) -> stac.LandingPage:
         if self.extension_is_enabled("FilterExtension"):
             landing_page["links"].append(
                 {
-                    # TODO: replace this with Relations.queryables.value,
-                    "rel": "http://www.opengis.net/def/rel/ogc/1.0/queryables",
-                    # TODO: replace this with MimeTypes.jsonschema,
-                    "type": "application/schema+json",
+                    "rel": Relations.queryables.value,
+                    "type": MimeTypes.jsonschema.value,
                     "title": "Queryables",
                     "href": urljoin(base_url, "queryables"),
                     "method": "GET",
diff --git a/stac_fastapi/types/stac_fastapi/types/rfc3339.py b/stac_fastapi/types/stac_fastapi/types/rfc3339.py
index a551b45d..5ba0630a 100644
--- a/stac_fastapi/types/stac_fastapi/types/rfc3339.py
+++ b/stac_fastapi/types/stac_fastapi/types/rfc3339.py
@@ -122,6 +122,9 @@ def str_to_interval(interval: Optional[str]) -> Optional[DateTimeType]:
             detail="Interval string contains more than one forward slash.",
         )
 
+    if len(values) == 1:
+        values = [values[0], values[0]]
+
     try:
         start = parse_single_date(values[0]) if values[0] not in ["..", ""] else None
         end = (