diff --git a/backend/src/services/secret-sync/secret-sync-schemas.ts b/backend/src/services/secret-sync/secret-sync-schemas.ts
index 9dab3c121..80e96bf8b 100644
--- a/backend/src/services/secret-sync/secret-sync-schemas.ts
+++ b/backend/src/services/secret-sync/secret-sync-schemas.ts
@@ -28,9 +28,9 @@ const BaseSyncOptionsSchema = <T extends AnyZodObject | undefined = undefined>({
     keySchema: z
       .string()
       .optional()
-      .refine((val) => !val || new RE2(/^(?:[a-zA-Z0-9\-/]*)(?:\{\{secretKey\}\})(?:[a-zA-Z0-9\-/]*)$/).test(val), {
+      .refine((val) => !val || new RE2(/^(?:[a-zA-Z0-9_\-/]*)(?:\{\{secretKey\}\})(?:[a-zA-Z0-9_\-/]*)$/).test(val), {
         message:
-          "Key schema must include one {{secretKey}} and only contain letters, numbers, dashes, slashes, and the {{secretKey}} placeholder."
+          "Key schema must include one {{secretKey}} and only contain letters, numbers, dashes, underscores, slashes, and the {{secretKey}} placeholder."
       })
       .describe(SecretSyncs.SYNC_OPTIONS(destination).keySchema),
     disableSecretDeletion: z.boolean().optional().describe(SecretSyncs.SYNC_OPTIONS(destination).disableSecretDeletion)
diff --git a/frontend/src/components/secret-syncs/forms/schemas/base-secret-sync-schema.ts b/frontend/src/components/secret-syncs/forms/schemas/base-secret-sync-schema.ts
index 4e858ac0d..75a5b68c1 100644
--- a/frontend/src/components/secret-syncs/forms/schemas/base-secret-sync-schema.ts
+++ b/frontend/src/components/secret-syncs/forms/schemas/base-secret-sync-schema.ts
@@ -13,10 +13,11 @@ export const BaseSecretSyncSchema = <T extends AnyZodObject | undefined = undefi
       .string()
       .optional()
       .refine(
-        (val) => !val || /^(?:[a-zA-Z0-9\-/]*)(?:\{\{secretKey\}\})(?:[a-zA-Z0-9\-/]*)$/.test(val),
+        (val) =>
+          !val || /^(?:[a-zA-Z0-9_\-/]*)(?:\{\{secretKey\}\})(?:[a-zA-Z0-9_\-/]*)$/.test(val),
         {
           message:
-            "Key schema must include one {{secretKey}} and only contain letters, numbers, dashes, slashes, and the {{secretKey}} placeholder."
+            "Key schema must include one {{secretKey}} and only contain letters, numbers, dashes, underscores, slashes, and the {{secretKey}} placeholder."
         }
       )
   });