diff --git a/data/api/server-server/definitions/event_hash.yaml b/data/api/server-server/definitions/event_hash.yaml
new file mode 100644
index 00000000..e12eaf05
--- /dev/null
+++ b/data/api/server-server/definitions/event_hash.yaml
@@ -0,0 +1,13 @@
+type: object
+title: Event Hash
+description: |-
+  Content hashes of the PDU, following the algorithm specified in [Signing Events](/server-server-api/#signing-events).
+example: {
+  "sha256": "ThisHashCoversAllFieldsInCaseThisIsRedacted"
+}
+properties:
+  sha256:
+    type: string
+    description: The hash.
+    example: ThisHashCoversAllFieldsInCaseThisIsRedacted
+required: ['sha256']
\ No newline at end of file
diff --git a/data/api/server-server/definitions/pdu.yaml b/data/api/server-server/definitions/pdu.yaml
index 5903f80e..00b83321 100644
--- a/data/api/server-server/definitions/pdu.yaml
+++ b/data/api/server-server/definitions/pdu.yaml
@@ -25,19 +25,7 @@ allOf:
         description: For redaction events, the ID of the event being redacted.
         example: "$def456:matrix.org"
       hashes:
-        type: object
-        title: Event Hash
-        description: |-
-          Content hashes of the PDU, following the algorithm specified in [Signing Events](/server-server-api/#signing-events).
-        example: {
-          "sha256": "ThisHashCoversAllFieldsInCaseThisIsRedacted"
-        }
-        properties:
-          sha256:
-            type: string
-            description: The hash.
-            example: ThisHashCoversAllFieldsInCaseThisIsRedacted
-        required: ['sha256']
+        $ref: "event_hash.yaml"
       signatures:
         type: object
         description: |-
diff --git a/data/api/server-server/definitions/pdu_v11.yaml b/data/api/server-server/definitions/pdu_v11.yaml
index 3edfb6c8..60f9b3ac 100644
--- a/data/api/server-server/definitions/pdu_v11.yaml
+++ b/data/api/server-server/definitions/pdu_v11.yaml
@@ -47,19 +47,7 @@ allOf:
           Must contain less than or equal to 20 events.
         example: ["$URLsafe-base64EncodedHash", "$Another_Event"]
       hashes:
-        type: object
-        title: Event Hash
-        description: |-
-          Content hashes of the PDU, following the algorithm specified in [Signing Events](/server-server-api/#signing-events).
-        example: {
-          "sha256": "ThisHashCoversAllFieldsInCaseThisIsRedacted"
-        }
-        properties:
-          sha256:
-            type: string
-            description: The hash.
-            example: ThisHashCoversAllFieldsInCaseThisIsRedacted
-        required: ['sha256']
+        $ref: "event_hash.yaml"
       signatures:
         type: object
         description: |-
diff --git a/data/api/server-server/definitions/pdu_v3.yaml b/data/api/server-server/definitions/pdu_v3.yaml
index 32d05b36..e801518c 100644
--- a/data/api/server-server/definitions/pdu_v3.yaml
+++ b/data/api/server-server/definitions/pdu_v3.yaml
@@ -49,19 +49,7 @@ allOf:
           Must contain less than or equal to 20 events.
         example: ["$base64EncodedHash", "$AnotherEvent"]
       hashes:
-        type: object
-        title: Event Hash
-        description: |-
-          Content hashes of the PDU, following the algorithm specified in [Signing Events](/server-server-api/#signing-events).
-        example: {
-          "sha256": "ThisHashCoversAllFieldsInCaseThisIsRedacted"
-        }
-        properties:
-          sha256:
-            type: string
-            description: The hash.
-            example: ThisHashCoversAllFieldsInCaseThisIsRedacted
-        required: ['sha256']
+        $ref: "event_hash.yaml"
       signatures:
         type: object
         description: |-
diff --git a/data/api/server-server/definitions/unsigned_pdu_base.yaml b/data/api/server-server/definitions/unsigned_pdu_base.yaml
index ce42236f..a2ec9552 100644
--- a/data/api/server-server/definitions/unsigned_pdu_base.yaml
+++ b/data/api/server-server/definitions/unsigned_pdu_base.yaml
@@ -60,17 +60,7 @@ properties:
           - type: string
             title: Event ID
             example: "$abc123:matrix.org"
-          - type: object
-            title: Event Hash
-            example: {
-              "sha256": "Base64EncodedSha256HashesShouldBe43BytesLong"
-            }
-            properties:
-              sha256:
-                type: string
-                description: The event hash.
-                example: Base64EncodedSha256HashesShouldBe43BytesLong
-            required: ['sha256']
+          - $ref: "event_hash.yaml"
   depth:
     type: integer
     description: |-
@@ -96,17 +86,7 @@ properties:
           - type: string
             title: Event ID
             example: "$abc123:matrix.org"
-          - type: object
-            title: Event Hash
-            example: {
-              "sha256": "Base64EncodedSha256HashesShouldBe43BytesLong"
-            }
-            properties:
-              sha256:
-                type: string
-                description: The event hash.
-                example: Base64EncodedSha256HashesShouldBe43BytesLong
-            required: ['sha256']
+          - $ref: "event_hash.yaml"
   unsigned:
     type: object
     title: UnsignedData