diff --git a/pyproject.toml b/pyproject.toml
index 79e6a91..f9c4d55 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -17,10 +17,10 @@ dependencies = [
     "pydantic",
     "tenacity",
     "jsonschema",
+    "cryptography",
     "PyYAML",
     "typing-extensions",
     "lightkube>=v0.15.4",
-    "charm-relation-interfaces @ git+https://github.com/canonical/charm-relation-interfaces",
 ]
 classifiers = [
     "Programming Language :: Python :: 3.8",
diff --git a/src/cosl/interfaces/datasource_exchange.py b/src/cosl/interfaces/datasource_exchange.py
index 9105e44..cd173e1 100644
--- a/src/cosl/interfaces/datasource_exchange.py
+++ b/src/cosl/interfaces/datasource_exchange.py
@@ -8,7 +8,6 @@
 for the interface specification.
 """
 
-
 # FIXME: the interfaces import (because it's a git dep perhaps?)
 #  can't be type-checked, which breaks everything
 # pyright: reportMissingImports=false
@@ -30,11 +29,8 @@
 )
 
 import ops
-from interfaces.grafana_datasource_exchange.v0.schema import (
-    GrafanaDatasource,
-    GrafanaSourceAppData,
-)
 from ops import CharmBase
+from pydantic import BaseModel, Field, Json
 from typing_extensions import TypedDict
 
 import cosl.interfaces.utils
@@ -45,6 +41,26 @@
 DS_EXCHANGE_INTERFACE_NAME = "grafana_datasource_exchange"
 
 
+# FIXME copy-pasta'd from charm-relation-interfaces. Keep in sync!
+#  see https://github.com/canonical/charm-relation-interfaces/issues/213
+class GrafanaDatasource(BaseModel):
+    """GrafanaDatasource model."""
+
+    type: str = Field(
+        description="Type of the datasource, typically one of "
+        "https://grafana.com/docs/grafana/latest/datasources/#built-in-core-data-sources.",
+        examples=["tempo", "loki", "prometheus", "elasticsearch"],
+    )
+    uid: str = Field(description="Grafana datasource UID, as assigned by Grafana.")
+    grafana_uid: str = Field(description="Grafana UID.")
+
+
+class GrafanaSourceAppData(BaseModel):
+    """Application databag model for both sides of this interface."""
+
+    datasources: Json[List[GrafanaDatasource]]
+
+
 class DSExchangeAppData(cosl.interfaces.utils.DatabagModelV2, GrafanaSourceAppData):
     """App databag schema for both sides of this interface."""
 
diff --git a/tests/test_datasource_exchange.py b/tests/test_datasource_exchange.py
index 9b6b57a..76250ef 100644
--- a/tests/test_datasource_exchange.py
+++ b/tests/test_datasource_exchange.py
@@ -1,7 +1,6 @@
 import json
 
 import pytest
-from interfaces.grafana_datasource_exchange.v0.schema import GrafanaDatasource
 from ops import CharmBase, Framework
 from scenario import Context, Relation, State
 from scenario.errors import UncaughtCharmError
@@ -10,6 +9,7 @@
     DatasourceExchange,
     DSExchangeAppData,
     EndpointValidationError,
+    GrafanaDatasource,
 )