diff --git a/src/ZenWorkspaces.mjs b/src/ZenWorkspaces.mjs
index e43699f..df1caa9 100644
--- a/src/ZenWorkspaces.mjs
+++ b/src/ZenWorkspaces.mjs
@@ -19,6 +19,7 @@ var ZenWorkspaces = new class extends ZenMultiWindowFeature {
       this._expandWorkspacesStrip.bind(this)
     );
     ChromeUtils.defineLazyGetter(this, 'tabContainer', () => document.getElementById('tabbrowser-tabs'));
+    await ZenWorkspacesStorage.init();
     await this.initializeWorkspaces();
     console.info('ZenWorkspaces: ZenWorkspaces initialized');
   }
@@ -57,10 +58,7 @@ var ZenWorkspaces = new class extends ZenMultiWindowFeature {
 
   async _workspaces() {
     if (!this._workspaceCache) {
-      this._workspaceCache = await IOUtils.readJSON(this._storeFile);
-      if (!this._workspaceCache.workspaces) {
-        this._workspaceCache.workspaces = [];
-      }
+      this._workspaceCache = { workspaces: await ZenWorkspacesStorage.getWorkspaces() };
     }
     return this._workspaceCache;
   }
@@ -171,42 +169,34 @@ var ZenWorkspaces = new class extends ZenMultiWindowFeature {
   }
 
   async saveWorkspace(workspaceData) {
-    let json = await IOUtils.readJSON(this._storeFile);
-    if (typeof json.workspaces === 'undefined') {
-      json.workspaces = [];
-    }
-    let existing = json.workspaces.findIndex((workspace) => workspace.uuid === workspaceData.uuid);
-    if (existing >= 0) {
-      json.workspaces[existing] = workspaceData;
-    } else {
-      json.workspaces.push(workspaceData);
-    }
-    console.info('ZenWorkspaces: Saving workspace', workspaceData);
-    await IOUtils.writeJSON(this._storeFile, json);
+    await ZenWorkspacesStorage.saveWorkspace(workspaceData);
     this._workspaceCache = null;
-
     await this._updateWorkspacesChangeContextMenu();
   }
 
   async removeWorkspace(windowID) {
-    let json = await this._workspaces();
     console.info('ZenWorkspaces: Removing workspace', windowID);
     await this.changeWorkspace(json.workspaces.find((workspace) => workspace.uuid !== windowID));
     this._deleteAllTabsInWorkspace(windowID);
     delete this._lastSelectedWorkspaceTabs[windowID];
-    json.workspaces = json.workspaces.filter((workspace) => workspace.uuid !== windowID);
-    await this.unsafeSaveWorkspaces(json);
+    await ZenWorkspacesStorage.removeWorkspace(windowID);
+    this._workspaceCache = null;
     await this._propagateWorkspaceData();
     await this._updateWorkspacesChangeContextMenu();
   }
 
   async saveWorkspaces() {
-    await IOUtils.writeJSON(this._storeFile, await this._workspaces());
+    const workspaces = await this._workspaces();
+    for (const workspace of workspaces.workspaces) {
+      await ZenWorkspacesStorage.saveWorkspace(workspace);
+    }
     this._workspaceCache = null;
   }
 
   async unsafeSaveWorkspaces(workspaces) {
-    await IOUtils.writeJSON(this._storeFile, workspaces);
+    for (const workspace of workspaces.workspaces) {
+      await ZenWorkspacesStorage.saveWorkspace(workspace);
+    }
     this._workspaceCache = workspaces;
   }
 
@@ -624,6 +614,8 @@ var ZenWorkspaces = new class extends ZenMultiWindowFeature {
 
       browser.document.getElementById('tabbrowser-tabs')._positionPinnedTabs();
     });
+
+    await ZenWorkspacesStorage.setActiveWorkspace(window.uuid);
     await this.saveWorkspaces();
     await this._propagateWorkspaceData();
   }
@@ -748,7 +740,7 @@ var ZenWorkspaces = new class extends ZenMultiWindowFeature {
 
   onContextMenuClose() {
     let target = document.querySelector(
-      `#PanelUI-zen-workspaces [zen-workspace-id="${this._contextMenuId}"] .zen-workspace-actions`
+        `#PanelUI-zen-workspaces [zen-workspace-id="${this._contextMenuId}"] .zen-workspace-actions`
     );
     if (target) {
       target.removeAttribute('active');
@@ -757,11 +749,8 @@ var ZenWorkspaces = new class extends ZenMultiWindowFeature {
   }
 
   async setDefaultWorkspace() {
-    let workspaces = await this._workspaces();
-    for (let workspace of workspaces.workspaces) {
-      workspace.default = workspace.uuid === this._contextMenuId;
-    }
-    await this.unsafeSaveWorkspaces(workspaces);
+    await ZenWorkspacesStorage.setDefaultWorkspace(this._contextMenuId);
+    this._workspaceCache = null;
     await this._propagateWorkspaceData();
   }
 
diff --git a/src/ZenWorkspacesStorage.mjs b/src/ZenWorkspacesStorage.mjs
new file mode 100644
index 0000000..325497d
--- /dev/null
+++ b/src/ZenWorkspacesStorage.mjs
@@ -0,0 +1,89 @@
+var ZenWorkspacesStorage = {
+  async init() {
+    console.log('ZenWorkspacesStorage: Initializing...');
+    await this._ensureTable();
+  },
+
+  async _ensureTable() {
+    await PlacesUtils.withConnectionWrapper("ZenWorkspacesStorage._ensureTable", async db => {
+      await db.execute(`
+        CREATE TABLE IF NOT EXISTS moz_workspaces (
+          id INTEGER PRIMARY KEY,
+          uuid TEXT UNIQUE NOT NULL,
+          name TEXT NOT NULL,
+          icon TEXT,
+          is_default INTEGER NOT NULL DEFAULT 0,
+          is_active INTEGER NOT NULL DEFAULT 0,
+          container_id INTEGER,
+          created_at INTEGER NOT NULL,
+          updated_at INTEGER NOT NULL
+        )
+      `);
+    });
+  },
+
+  async saveWorkspace(workspace) {
+    await PlacesUtils.withConnectionWrapper("ZenWorkspacesStorage.saveWorkspace", async db => {
+      const now = Date.now();
+      await db.executeCached(`
+        INSERT OR REPLACE INTO moz_workspaces (
+          uuid, name, icon, is_default, is_active, container_id, created_at, updated_at
+        ) VALUES (
+          :uuid, :name, :icon, :is_default, :is_active, :container_id, 
+          COALESCE((SELECT created_at FROM moz_workspaces WHERE uuid = :uuid), :now),
+          :now
+        )
+      `, {
+        uuid: workspace.uuid,
+        name: workspace.name,
+        icon: workspace.icon || null,
+        is_default: workspace.default ? 1 : 0,
+        is_active: workspace.used ? 1 : 0,
+        container_id: workspace.containerTabId || null,
+        now
+      });
+    });
+  },
+
+  async getWorkspaces() {
+    const db = await PlacesUtils.promiseDBConnection();
+    const rows = await db.execute(`
+      SELECT * FROM moz_workspaces ORDER BY created_at ASC
+    `);
+
+    return rows.map(row => ({
+      uuid: row.getResultByName("uuid"),
+      name: row.getResultByName("name"),
+      icon: row.getResultByName("icon"),
+      default: !!row.getResultByName("is_default"),
+      used: !!row.getResultByName("is_active"),
+      containerTabId: row.getResultByName("container_id")
+    }));
+  },
+
+  async removeWorkspace(uuid) {
+    await PlacesUtils.withConnectionWrapper("ZenWorkspacesStorage.removeWorkspace", async db => {
+      await db.execute(`
+        DELETE FROM moz_workspaces WHERE uuid = :uuid
+      `, { uuid });
+    });
+  },
+
+  async setActiveWorkspace(uuid) {
+    await PlacesUtils.withConnectionWrapper("ZenWorkspacesStorage.setActiveWorkspace", async db => {
+      await db.executeTransaction(async function() {
+        await db.execute(`UPDATE moz_workspaces SET is_active = 0`);
+        await db.execute(`UPDATE moz_workspaces SET is_active = 1 WHERE uuid = :uuid`, { uuid });
+      });
+    });
+  },
+
+  async setDefaultWorkspace(uuid) {
+    await PlacesUtils.withConnectionWrapper("ZenWorkspacesStorage.setDefaultWorkspace", async db => {
+      await db.executeTransaction(async function() {
+        await db.execute(`UPDATE moz_workspaces SET is_default = 0`);
+        await db.execute(`UPDATE moz_workspaces SET is_default = 1 WHERE uuid = :uuid`, { uuid });
+      });
+    });
+  }
+};
\ No newline at end of file