diff --git a/src/base.js b/src/base.js
index ee9376a..5bfe09c 100644
--- a/src/base.js
+++ b/src/base.js
@@ -1,4 +1,5 @@
 const _ = require('lodash');
+const assert = require('assert');
 const debug = require('debug')('taskcluster-lib-monitor');
 
 /**
@@ -169,6 +170,9 @@ class BaseMonitor {
 
     try {
       try {
+        assert.equal(typeof name, 'string');
+        assert.equal(typeof fn, 'function');
+
         await this.timer(`${name}.duration`, fn);
         this.count(`${name}.done`);
       } catch (err) {
diff --git a/src/mockmonitor.js b/src/mockmonitor.js
index 4de2c88..ff1aa7a 100644
--- a/src/mockmonitor.js
+++ b/src/mockmonitor.js
@@ -64,6 +64,9 @@ class MockMonitor extends BaseMonitor {
    * Override oneShot to helpfully not call process.exit
    */
   async oneShot(name, fn) {
+    assert.equal(typeof name, 'string');
+    assert.equal(typeof fn, 'function');
+
     await fn();
   }
 }
diff --git a/test/base_test.js b/test/base_test.js
index 9a7391d..ed2867e 100644
--- a/test/base_test.js
+++ b/test/base_test.js
@@ -117,5 +117,11 @@ suite('BaseMonitor', function() {
       assert.equal(monitor.counts.length, 0);
       assert(monitor.errors[0].toString().match(/uhoh/), monitor.errors[0]);
     });
+
+    test('missing name', async function() {
+      await monitor.oneShot(async () => { throw new Error('uhoh'); });
+      assert.equal(exitStatus, 1);
+      assert(monitor.errors[0].toString().match(/Assertion/), monitor.errors[0]);
+    });
   });
 });
diff --git a/test/mockmonitor_test.js b/test/mockmonitor_test.js
index fef4742..5bd7938 100644
--- a/test/mockmonitor_test.js
+++ b/test/mockmonitor_test.js
@@ -155,7 +155,7 @@ suite('MockMonitor', () => {
   });
 
   test('monitor.oneShot', async () => {
-    monitor.oneShot(() => {});
+    await monitor.oneShot('test', () => {});
     // just expect this not to call process.exit!
   });
 });