diff --git a/inspire_schemas/records/institutions.yml b/inspire_schemas/records/institutions.yml
index dc06edb2..dce5744f 100644
--- a/inspire_schemas/records/institutions.yml
+++ b/inspire_schemas/records/institutions.yml
@@ -99,6 +99,26 @@ properties:
             List of identifiers of this institution on external systems.
         items:
             anyOf:
+            -   additionalProperties: false
+                properties:
+                    schema:
+                        description: |-
+                            :MARC: ``035__9:GRID``
+                        enum:
+                        - GRID
+                        minLength: 1
+                        type: string
+                    value:
+                        description: |-
+                            :MARC: ``035__a``
+                        minLength: 1
+                        pattern: ^grid\.\d+\.\w+$
+                        type: string
+                required:
+                - schema
+                - value
+                title: GRID identifier
+                type: object
             -   additionalProperties: false
                 properties:
                     schema: