diff --git a/migrations/20201028052525-volumes-create-table.js b/migrations/20201028052525-volumes-create-table.js
index d8c2ed5ce..245d98b41 100644
--- a/migrations/20201028052525-volumes-create-table.js
+++ b/migrations/20201028052525-volumes-create-table.js
@@ -12,6 +12,7 @@ exports.up = function(db, callback) {
                  'appId VARCHAR(128) NOT NULL,' +
                  'volumeId VARCHAR(128) NOT NULL,' +
                  'readOnly BOOLEAN DEFAULT 1,' +
+                 'UNIQUE KEY appMounts_appId_volumeId (appId, volumeId),' +
                  'FOREIGN KEY(appId) REFERENCES apps(id),' +
                  'FOREIGN KEY(volumeId) REFERENCES volumes(id)) CHARACTER SET utf8 COLLATE utf8_bin;';
 
diff --git a/migrations/schema.sql b/migrations/schema.sql
index ae9fb9c36..cd56350b6 100644
--- a/migrations/schema.sql
+++ b/migrations/schema.sql
@@ -85,7 +85,6 @@ CREATE TABLE IF NOT EXISTS apps(
     dataDir VARCHAR(256) UNIQUE,
     taskId INTEGER, // current task
     errorJson TEXT,
-    bindsJson TEXT, // bind mounts
     servicesConfigJson TEXT, // app services configuration
 
     FOREIGN KEY(mailboxDomain) REFERENCES domains(domain),
@@ -248,6 +247,8 @@ CREATE TABLE IF NOT EXISTS volumes(
 CREATE TABLE IF NOT EXISTS appMounts(
     appId VARCHAR(128) NOT NULL,
     volumeId VARCHAR(128) NOT NULL,
+    readOnly BOOLEAN DEFAULT 1,
+    UNIQUE KEY appMounts_appId_volumeId (appId, volumeId),
     FOREIGN KEY(appId) REFERENCES apps(id),
     FOREIGN KEY(volumeId) REFERENCES volumes(id));
 
diff --git a/src/apps.js b/src/apps.js
index 46a0abc6d..b78a10622 100644
--- a/src/apps.js
+++ b/src/apps.js
@@ -995,6 +995,7 @@ function setMounts(app, mounts, auditSource, callback) {
         values: { mounts }
     };
     addTask(appId, exports.ISTATE_PENDING_RECREATE_CONTAINER, task, function (error, result) {
+        if (error && error.reason === BoxError.ALREADY_EXISTS) return callback(new BoxError(BoxError.CONFLICT, 'Duplicate mount points'));
         if (error) return callback(error);
 
         eventlog.add(eventlog.ACTION_APP_CONFIGURE, auditSource, { appId, app, mounts, taskId: result.taskId });