diff --git a/extensions/ql-vscode/src/query-serialization.ts b/extensions/ql-vscode/src/query-serialization.ts
index e5508639fd2..a242380e104 100644
--- a/extensions/ql-vscode/src/query-serialization.ts
+++ b/extensions/ql-vscode/src/query-serialization.ts
@@ -14,7 +14,13 @@ export async function slurpQueryHistory(fsPath: string, config: QueryHistoryConf
     }
 
     const data = await fs.readFile(fsPath, 'utf8');
-    const queries = JSON.parse(data);
+    const obj = JSON.parse(data);
+    if (obj.version !== 1) {
+      void showAndLogErrorMessage(`Unsupported query history format: v${obj.version}. `);
+      return [];
+    }
+
+    const queries = obj.queries;
     const parsedQueries = queries.map((q: QueryHistoryInfo) => {
 
       // Need to explicitly set prototype since reading in from JSON will not
@@ -82,7 +88,10 @@ export async function splatQueryHistory(queries: QueryHistoryInfo[], fsPath: str
     }
     // remove incomplete local queries since they cannot be recreated on restart
     const filteredQueries = queries.filter(q => q.t === 'local' ? q.completedQuery !== undefined : true);
-    const data = JSON.stringify(filteredQueries, null, 2);
+    const data = JSON.stringify({
+      version: 1,
+      queries: filteredQueries
+    }, null, 2);
     await fs.writeFile(fsPath, data);
   } catch (e) {
     throw new Error(`Error saving query history to ${fsPath}: ${e.message}`);
diff --git a/extensions/ql-vscode/src/vscode-tests/no-workspace/query-results.test.ts b/extensions/ql-vscode/src/vscode-tests/no-workspace/query-results.test.ts
index 05e3742d396..0aa6843fc49 100644
--- a/extensions/ql-vscode/src/vscode-tests/no-workspace/query-results.test.ts
+++ b/extensions/ql-vscode/src/vscode-tests/no-workspace/query-results.test.ts
@@ -254,20 +254,30 @@ describe('query-results', () => {
   });
 
   describe('splat and slurp', () => {
-    it('should splat and slurp query history', async () => {
-      const infoSuccessRaw = createMockFullQueryInfo('a', createMockQueryWithResults(`${queryPath}-a`, false, false, '/a/b/c/a', false));
-      const infoSuccessInterpreted = createMockFullQueryInfo('b', createMockQueryWithResults(`${queryPath}-b`, true, true, '/a/b/c/b', false));
-      const infoEarlyFailure = createMockFullQueryInfo('c', undefined, true);
-      const infoLateFailure = createMockFullQueryInfo('d', createMockQueryWithResults(`${queryPath}-c`, false, false, '/a/b/c/d', false));
-      const infoInprogress = createMockFullQueryInfo('e');
-      const allHistory = [
+
+    let infoSuccessRaw: LocalQueryInfo;
+    let infoSuccessInterpreted: LocalQueryInfo;
+    let infoEarlyFailure: LocalQueryInfo;
+    let infoLateFailure: LocalQueryInfo;
+    let infoInprogress: LocalQueryInfo;
+    let allHistory: LocalQueryInfo[];
+
+    beforeEach(() => {
+      infoSuccessRaw = createMockFullQueryInfo('a', createMockQueryWithResults(`${queryPath}-a`, false, false, '/a/b/c/a', false));
+      infoSuccessInterpreted = createMockFullQueryInfo('b', createMockQueryWithResults(`${queryPath}-b`, true, true, '/a/b/c/b', false));
+      infoEarlyFailure = createMockFullQueryInfo('c', undefined, true);
+      infoLateFailure = createMockFullQueryInfo('d', createMockQueryWithResults(`${queryPath}-c`, false, false, '/a/b/c/d', false));
+      infoInprogress = createMockFullQueryInfo('e');
+      allHistory = [
         infoSuccessRaw,
         infoSuccessInterpreted,
         infoEarlyFailure,
         infoLateFailure,
         infoInprogress
       ];
+    });
 
+    it('should splat and slurp query history', async () => {
       // the expected results only contains the history with completed queries
       const expectedHistory = [
         infoSuccessRaw,
@@ -313,6 +323,18 @@ describe('query-results', () => {
       }
       expect(allHistoryActual.length).to.deep.eq(expectedHistory.length);
     });
+
+    it('should handle an invalid query history version', async () => {
+      const badPath = path.join(tmpDir.name, 'bad-query-history.json');
+      fs.writeFileSync(badPath, JSON.stringify({
+        version: 2,
+        queries: allHistory
+      }), 'utf8');
+
+      const allHistoryActual = await slurpQueryHistory(badPath, mockConfig);
+      // version number is invalid. Should return an empty array.
+      expect(allHistoryActual).to.deep.eq([]);
+    });
   });
 
   function createMockQueryWithResults(