diff --git a/event_model/documents/event_descriptor.py b/event_model/documents/event_descriptor.py
index 3c4a2bfa..ec8f8cfd 100644
--- a/event_model/documents/event_descriptor.py
+++ b/event_model/documents/event_descriptor.py
@@ -98,7 +98,12 @@ class Configuration(TypedDict):
             "patternProperties": {"^([^./]+)$": {"$ref": "#/definitions/DataType"}},
             "additionalProperties": False,
         },
-        "DataKey": {"properties": {"units": {"type": ["string", "null"]}}},
+        "DataKey": {
+            "properties": {
+                "units": {"type": ["string", "null"]},
+                "precision": {"type": ["integer", "null"]}
+            }
+        },
     },
     "additionalProperties": False,
 }
diff --git a/event_model/schemas/event_descriptor.json b/event_model/schemas/event_descriptor.json
index adcc1cc0..ecd039b2 100644
--- a/event_model/schemas/event_descriptor.json
+++ b/event_model/schemas/event_descriptor.json
@@ -66,7 +66,10 @@
             "precision": {
                "title": "Precision",
                "description": "Number of digits after decimal place if a floating point number",
-               "type": "integer"
+               "type": [
+                  "integer",
+                  "null"
+               ]
             },
             "shape": {
                "title": "Shape",