diff --git a/.github/requirements_min.txt b/.github/requirements_min.txt
index 02c2602a..c315e132 100644
--- a/.github/requirements_min.txt
+++ b/.github/requirements_min.txt
@@ -4,6 +4,7 @@ cycler==0.10.0
 docstring-parser==0.16
 matplotlib==3.3.0
 numpy==1.22.0
+packaging==24.1
 pydantic==2.7.0
 pyglotaran==0.7.0
 ruamel-yaml==0.18.6
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 772b24f0..ac822eb6 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -36,6 +36,7 @@ repos:
     rev: v4.0.0-alpha.8 # Use the sha or tag you want to point at
     hooks:
       - id: prettier
+        additional_dependencies: ["prettier@3.3.3"]
 
   # Notebook tools
   - repo: https://github.com/kynan/nbstripout
diff --git a/pyglotaran_extras/config/config.py b/pyglotaran_extras/config/config.py
index 698edd43..21c673e3 100644
--- a/pyglotaran_extras/config/config.py
+++ b/pyglotaran_extras/config/config.py
@@ -9,10 +9,12 @@
 from typing import TYPE_CHECKING
 from typing import Any
 
+from packaging.version import Version
 from pydantic import BaseModel
 from pydantic import ConfigDict
 from pydantic import PrivateAttr
 from pydantic import PydanticUserError
+from pydantic import __version__ as pydantic_version
 from pydantic import create_model
 from pydantic.fields import FieldInfo
 from ruamel.yaml import YAML
@@ -447,9 +449,11 @@ def create_config_schema(
             general_kwargs |= func_json_schema["$defs"][kwargs_model_name]["properties"]
             json_schema["$defs"] |= func_json_schema.pop("$defs")
             json_schema["$defs"][config_model_name] = func_json_schema
-            json_schema["$defs"]["PlotConfig"]["properties"][function_name] = {
-                "allOf": [{"$ref": f"#/$defs/{config_model_name}"}]
-            }
+            json_schema["$defs"]["PlotConfig"]["properties"][function_name] = (
+                {"$ref": f"#/$defs/{config_model_name}"}
+                if Version(pydantic_version) >= Version("2.9")
+                else {"allOf": [{"$ref": f"#/$defs/{config_model_name}"}]}  # type:ignore[dict-item]
+            )
         except PydanticUserError as error:
             raise UsePlotConfigError(function_name, error)  # noqa: B904
     json_schema["$defs"]["PerFunctionPlotConfig"]["properties"]["default_args_override"][
diff --git a/pyproject.toml b/pyproject.toml
index 407fbf01..c4f4c605 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -36,6 +36,7 @@ dependencies = [
   "docstring-parser>=0.16",
   "matplotlib>=3.3",
   "numpy>=1.22",
+  "packaging>=24.1",
   "pydantic>=2.7",
   "pyglotaran>=0.7",
   "ruamel-yaml>=0.18.6",
diff --git a/requirements_pinned.txt b/requirements_pinned.txt
index 6490b507..e69358d3 100644
--- a/requirements_pinned.txt
+++ b/requirements_pinned.txt
@@ -1,11 +1,12 @@
-# Runtime dependencies
-
+# This file was autogenerated by uv via the following command:
+#    uv pip compile pyproject.toml -o requirements_pinned.txt --no-deps --no-annotate
 cycler==0.12.1
-numpy==1.26.4
+docstring-parser==0.16
 matplotlib==3.9.2
+numpy==1.26.4
+packaging==24.1
+pydantic==2.9.2
 pyglotaran==0.7.3
+ruamel-yaml==0.18.6
 tabulate==0.9.0
 xarray==2024.7.0
-ruamel.yaml==0.18.6
-docstring_parser==0.16
-pydantic==2.9.2
diff --git a/tests/config/test_config.py b/tests/config/test_config.py
index 2ed883c1..9a3736f7 100644
--- a/tests/config/test_config.py
+++ b/tests/config/test_config.py
@@ -11,6 +11,8 @@
 
 import pytest
 from jsonschema import Draft202012Validator
+from packaging.version import Version
+from pydantic import __version__ as pydantic_version
 from ruamel.yaml import YAML
 
 from pyglotaran_extras import create_config_schema
@@ -563,6 +565,8 @@ def test_func(
     json_schema = json.loads(create_config_schema(tmp_path).read_text())
     expected_schema = json.loads(
         (TEST_DATA / f"config/{CONFIG_FILE_STEM}.schema.json").read_text()
+        if Version(pydantic_version) >= Version("2.9")
+        else (TEST_DATA / f"config/{CONFIG_FILE_STEM}.schema.pydantic_lt_2_9.json").read_text()
     )
 
     assert json_schema == expected_schema
@@ -585,7 +589,13 @@ def test_func(
         pass
 
     json_schema = json.loads(create_config_schema(tmp_path).read_text())
-    expected_schema = json.loads((TEST_DATA / "config/broken_config.schema.json").read_text())
+    expected_schema = (
+        json.loads((TEST_DATA / "config/broken_config.schema.json").read_text())
+        if Version(pydantic_version) >= Version("2.9")
+        else json.loads(
+            (TEST_DATA / "config/broken_config.schema.pydantic_lt_2_9.json").read_text()
+        )
+    )
 
     assert json_schema == expected_schema
 
diff --git a/tests/data/config/broken_config.schema.json b/tests/data/config/broken_config.schema.json
index 3b7a107d..171f56e1 100644
--- a/tests/data/config/broken_config.schema.json
+++ b/tests/data/config/broken_config.schema.json
@@ -39,19 +39,11 @@
       "description": "Config for plot functions including default args and label overrides.",
       "properties": {
         "general": {
-          "allOf": [
-            {
-              "$ref": "#/$defs/PerFunctionPlotConfig"
-            }
-          ],
+          "$ref": "#/$defs/PerFunctionPlotConfig",
           "description": "Config that gets applied to all functions if not specified otherwise."
         },
         "test_func": {
-          "allOf": [
-            {
-              "$ref": "#/$defs/TestFuncConfig"
-            }
-          ]
+          "$ref": "#/$defs/TestFuncConfig"
         }
       },
       "title": "PlotConfig",
@@ -108,19 +100,11 @@
       "description": "Plot function configuration specific to ``test_func`` (overrides values in general).",
       "properties": {
         "default_args_override": {
-          "allOf": [
-            {
-              "$ref": "#/$defs/TestFuncKwargs"
-            }
-          ],
+          "$ref": "#/$defs/TestFuncKwargs",
           "default": {}
         },
         "axis_label_override": {
-          "allOf": [
-            {
-              "$ref": "#/$defs/PlotLabelOverrideMap"
-            }
-          ],
+          "$ref": "#/$defs/PlotLabelOverrideMap",
           "default": {}
         }
       },
@@ -132,11 +116,7 @@
   "description": "Main configuration class.",
   "properties": {
     "plotting": {
-      "allOf": [
-        {
-          "$ref": "#/$defs/PlotConfig"
-        }
-      ],
+      "$ref": "#/$defs/PlotConfig",
       "default": {
         "general": {}
       }
diff --git a/tests/data/config/broken_config.schema.pydantic_lt_2_9.json b/tests/data/config/broken_config.schema.pydantic_lt_2_9.json
new file mode 100644
index 00000000..3b7a107d
--- /dev/null
+++ b/tests/data/config/broken_config.schema.pydantic_lt_2_9.json
@@ -0,0 +1,147 @@
+{
+  "$defs": {
+    "PerFunctionPlotConfig": {
+      "additionalProperties": false,
+      "description": "Per function plot configuration.",
+      "properties": {
+        "default_args_override": {
+          "description": "Default arguments to use if not specified in function call.",
+          "title": "Default Args Override",
+          "type": "object",
+          "properties": {
+            "will_update_arg": {
+              "default": "default update",
+              "title": "Will Update Arg"
+            }
+          },
+          "additionalProperties": false
+        },
+        "axis_label_override": {
+          "anyOf": [
+            {
+              "$ref": "#/$defs/PlotLabelOverrideMap"
+            },
+            {
+              "additionalProperties": {
+                "type": "string"
+              },
+              "type": "object"
+            }
+          ],
+          "title": "Axis Label Override"
+        }
+      },
+      "title": "PerFunctionPlotConfig",
+      "type": "object"
+    },
+    "PlotConfig": {
+      "additionalProperties": true,
+      "description": "Config for plot functions including default args and label overrides.",
+      "properties": {
+        "general": {
+          "allOf": [
+            {
+              "$ref": "#/$defs/PerFunctionPlotConfig"
+            }
+          ],
+          "description": "Config that gets applied to all functions if not specified otherwise."
+        },
+        "test_func": {
+          "allOf": [
+            {
+              "$ref": "#/$defs/TestFuncConfig"
+            }
+          ]
+        }
+      },
+      "title": "PlotConfig",
+      "type": "object"
+    },
+    "PlotLabelOverrideMap": {
+      "additionalProperties": {
+        "anyOf": [
+          {
+            "$ref": "#/$defs/PlotLabelOverrideValue"
+          },
+          {
+            "type": "string"
+          }
+        ]
+      },
+      "description": "Mapping to override axis labels.",
+      "title": "PlotLabelOverrideMap",
+      "type": "object"
+    },
+    "PlotLabelOverrideValue": {
+      "additionalProperties": false,
+      "description": "Value of ``PlotLabelOverrideMap``.",
+      "properties": {
+        "target_name": {
+          "title": "Target Name",
+          "type": "string"
+        },
+        "axis": {
+          "default": "both",
+          "enum": ["x", "y", "both"],
+          "title": "Axis",
+          "type": "string"
+        }
+      },
+      "required": ["target_name"],
+      "title": "PlotLabelOverrideValue",
+      "type": "object"
+    },
+    "TestFuncKwargs": {
+      "additionalProperties": false,
+      "description": "Default arguments to use for ``test_func``, if not specified in function call.",
+      "properties": {
+        "will_update_arg": {
+          "default": "default update",
+          "title": "Will Update Arg"
+        }
+      },
+      "title": "TestFuncKwargs",
+      "type": "object"
+    },
+    "TestFuncConfig": {
+      "additionalProperties": false,
+      "description": "Plot function configuration specific to ``test_func`` (overrides values in general).",
+      "properties": {
+        "default_args_override": {
+          "allOf": [
+            {
+              "$ref": "#/$defs/TestFuncKwargs"
+            }
+          ],
+          "default": {}
+        },
+        "axis_label_override": {
+          "allOf": [
+            {
+              "$ref": "#/$defs/PlotLabelOverrideMap"
+            }
+          ],
+          "default": {}
+        }
+      },
+      "title": "TestFuncConfig",
+      "type": "object"
+    }
+  },
+  "additionalProperties": false,
+  "description": "Main configuration class.",
+  "properties": {
+    "plotting": {
+      "allOf": [
+        {
+          "$ref": "#/$defs/PlotConfig"
+        }
+      ],
+      "default": {
+        "general": {}
+      }
+    }
+  },
+  "title": "Config",
+  "type": "object"
+}
diff --git a/tests/data/config/pygta_config.schema.json b/tests/data/config/pygta_config.schema.json
index fee60dec..1f19ec9c 100644
--- a/tests/data/config/pygta_config.schema.json
+++ b/tests/data/config/pygta_config.schema.json
@@ -47,26 +47,14 @@
       "description": "Config for plot functions including default args and label overrides.",
       "properties": {
         "general": {
-          "allOf": [
-            {
-              "$ref": "#/$defs/PerFunctionPlotConfig"
-            }
-          ],
+          "$ref": "#/$defs/PerFunctionPlotConfig",
           "description": "Config that gets applied to all functions if not specified otherwise."
         },
         "other": {
-          "allOf": [
-            {
-              "$ref": "#/$defs/OtherConfig"
-            }
-          ]
+          "$ref": "#/$defs/OtherConfig"
         },
         "test_func": {
-          "allOf": [
-            {
-              "$ref": "#/$defs/TestFuncConfig"
-            }
-          ]
+          "$ref": "#/$defs/TestFuncConfig"
         }
       },
       "title": "PlotConfig",
@@ -123,19 +111,11 @@
       "description": "Plot function configuration specific to ``other`` (overrides values in general).",
       "properties": {
         "default_args_override": {
-          "allOf": [
-            {
-              "$ref": "#/$defs/OtherKwargs"
-            }
-          ],
+          "$ref": "#/$defs/OtherKwargs",
           "default": {}
         },
         "axis_label_override": {
-          "allOf": [
-            {
-              "$ref": "#/$defs/PlotLabelOverrideMap"
-            }
-          ],
+          "$ref": "#/$defs/PlotLabelOverrideMap",
           "default": {}
         }
       },
@@ -167,19 +147,11 @@
       "description": "Plot function configuration specific to ``test_func`` (overrides values in general).",
       "properties": {
         "default_args_override": {
-          "allOf": [
-            {
-              "$ref": "#/$defs/TestFuncKwargs"
-            }
-          ],
+          "$ref": "#/$defs/TestFuncKwargs",
           "default": {}
         },
         "axis_label_override": {
-          "allOf": [
-            {
-              "$ref": "#/$defs/PlotLabelOverrideMap"
-            }
-          ],
+          "$ref": "#/$defs/PlotLabelOverrideMap",
           "default": {}
         }
       },
@@ -191,11 +163,7 @@
   "description": "Main configuration class.",
   "properties": {
     "plotting": {
-      "allOf": [
-        {
-          "$ref": "#/$defs/PlotConfig"
-        }
-      ],
+      "$ref": "#/$defs/PlotConfig",
       "default": {
         "general": {}
       }
diff --git a/tests/data/config/pygta_config.schema.pydantic_lt_2_9.json b/tests/data/config/pygta_config.schema.pydantic_lt_2_9.json
new file mode 100644
index 00000000..fee60dec
--- /dev/null
+++ b/tests/data/config/pygta_config.schema.pydantic_lt_2_9.json
@@ -0,0 +1,206 @@
+{
+  "$defs": {
+    "PerFunctionPlotConfig": {
+      "additionalProperties": false,
+      "description": "Per function plot configuration.",
+      "properties": {
+        "default_args_override": {
+          "description": "Default arguments to use if not specified in function call.",
+          "title": "Default Args Override",
+          "type": "object",
+          "properties": {
+            "will_be_kept_arg": {
+              "default": "default keep",
+              "title": "Will Be Kept Arg"
+            },
+            "will_update_arg": {
+              "default": "default update",
+              "title": "Will Update Arg"
+            },
+            "will_be_added_arg": {
+              "default": "default add",
+              "title": "Will Be Added Arg"
+            }
+          },
+          "additionalProperties": false
+        },
+        "axis_label_override": {
+          "anyOf": [
+            {
+              "$ref": "#/$defs/PlotLabelOverrideMap"
+            },
+            {
+              "additionalProperties": {
+                "type": "string"
+              },
+              "type": "object"
+            }
+          ],
+          "title": "Axis Label Override"
+        }
+      },
+      "title": "PerFunctionPlotConfig",
+      "type": "object"
+    },
+    "PlotConfig": {
+      "additionalProperties": true,
+      "description": "Config for plot functions including default args and label overrides.",
+      "properties": {
+        "general": {
+          "allOf": [
+            {
+              "$ref": "#/$defs/PerFunctionPlotConfig"
+            }
+          ],
+          "description": "Config that gets applied to all functions if not specified otherwise."
+        },
+        "other": {
+          "allOf": [
+            {
+              "$ref": "#/$defs/OtherConfig"
+            }
+          ]
+        },
+        "test_func": {
+          "allOf": [
+            {
+              "$ref": "#/$defs/TestFuncConfig"
+            }
+          ]
+        }
+      },
+      "title": "PlotConfig",
+      "type": "object"
+    },
+    "PlotLabelOverrideMap": {
+      "additionalProperties": {
+        "anyOf": [
+          {
+            "$ref": "#/$defs/PlotLabelOverrideValue"
+          },
+          {
+            "type": "string"
+          }
+        ]
+      },
+      "description": "Mapping to override axis labels.",
+      "title": "PlotLabelOverrideMap",
+      "type": "object"
+    },
+    "PlotLabelOverrideValue": {
+      "additionalProperties": false,
+      "description": "Value of ``PlotLabelOverrideMap``.",
+      "properties": {
+        "target_name": {
+          "title": "Target Name",
+          "type": "string"
+        },
+        "axis": {
+          "default": "both",
+          "enum": ["x", "y", "both"],
+          "title": "Axis",
+          "type": "string"
+        }
+      },
+      "required": ["target_name"],
+      "title": "PlotLabelOverrideValue",
+      "type": "object"
+    },
+    "OtherKwargs": {
+      "additionalProperties": false,
+      "description": "Default arguments to use for ``other``, if not specified in function call.",
+      "properties": {
+        "will_be_kept_arg": {
+          "default": "default update",
+          "title": "Will Be Kept Arg"
+        }
+      },
+      "title": "OtherKwargs",
+      "type": "object"
+    },
+    "OtherConfig": {
+      "additionalProperties": false,
+      "description": "Plot function configuration specific to ``other`` (overrides values in general).",
+      "properties": {
+        "default_args_override": {
+          "allOf": [
+            {
+              "$ref": "#/$defs/OtherKwargs"
+            }
+          ],
+          "default": {}
+        },
+        "axis_label_override": {
+          "allOf": [
+            {
+              "$ref": "#/$defs/PlotLabelOverrideMap"
+            }
+          ],
+          "default": {}
+        }
+      },
+      "title": "OtherConfig",
+      "type": "object"
+    },
+    "TestFuncKwargs": {
+      "additionalProperties": false,
+      "description": "Default arguments to use for ``test_func``, if not specified in function call.",
+      "properties": {
+        "will_update_arg": {
+          "default": "default update",
+          "title": "Will Update Arg"
+        },
+        "will_be_kept_arg": {
+          "default": "default keep",
+          "title": "Will Be Kept Arg"
+        },
+        "will_be_added_arg": {
+          "default": "default add",
+          "title": "Will Be Added Arg"
+        }
+      },
+      "title": "TestFuncKwargs",
+      "type": "object"
+    },
+    "TestFuncConfig": {
+      "additionalProperties": false,
+      "description": "Plot function configuration specific to ``test_func`` (overrides values in general).",
+      "properties": {
+        "default_args_override": {
+          "allOf": [
+            {
+              "$ref": "#/$defs/TestFuncKwargs"
+            }
+          ],
+          "default": {}
+        },
+        "axis_label_override": {
+          "allOf": [
+            {
+              "$ref": "#/$defs/PlotLabelOverrideMap"
+            }
+          ],
+          "default": {}
+        }
+      },
+      "title": "TestFuncConfig",
+      "type": "object"
+    }
+  },
+  "additionalProperties": false,
+  "description": "Main configuration class.",
+  "properties": {
+    "plotting": {
+      "allOf": [
+        {
+          "$ref": "#/$defs/PlotConfig"
+        }
+      ],
+      "default": {
+        "general": {}
+      }
+    }
+  },
+  "title": "Config",
+  "type": "object"
+}