diff --git a/src/__tests__/old-act.js b/src/__tests__/old-act.js
index fcd531b4..0116ba7c 100644
--- a/src/__tests__/old-act.js
+++ b/src/__tests__/old-act.js
@@ -32,18 +32,15 @@ test('async act works even when the act is an old one', async () => {
     console.error('sigil')
   })
   expect(console.error.mock.calls).toMatchInlineSnapshot(`
-        Array [
-          Array [
-            "sigil",
-          ],
-          Array [
-            "It looks like you're using a version of react-dom that supports the \\"act\\" function, but not an awaitable version of \\"act\\" which you will need. Please upgrade to at least react-dom@16.9.0 to remove this warning.",
-          ],
-          Array [
-            "sigil",
-          ],
-        ]
-    `)
+    Array [
+      Array [
+        "It looks like you're using a version of react-dom that supports the \\"act\\" function, but not an awaitable version of \\"act\\" which you will need. Please upgrade to at least react-dom@16.9.0 to remove this warning.",
+      ],
+      Array [
+        "sigil",
+      ],
+    ]
+  `)
   expect(callback).toHaveBeenCalledTimes(1)
 
   // and it doesn't warn you twice
@@ -98,4 +95,28 @@ test('async act recovers from sync errors', async () => {
   `)
 })
 
+test('async act handles values that are not strings', async () => {
+  try {
+    await asyncAct(async () => {
+      console.error({message: 'some message'})
+      await null
+    })
+  } catch (err) {
+    console.error('call console.error')
+  }
+  expect(console.error).toHaveBeenCalledTimes(2)
+  expect(console.error.mock.calls).toMatchInlineSnapshot(`
+    Array [
+      Array [
+        Object {
+          "message": "some message",
+        },
+      ],
+      Array [
+        "It looks like you're using a version of react-dom that supports the \\"act\\" function, but not an awaitable version of \\"act\\" which you will need. Please upgrade to at least react-dom@16.9.0 to remove this warning.",
+      ],
+    ]
+  `)
+})
+
 /* eslint no-console:0 */
diff --git a/src/act-compat.js b/src/act-compat.js
index dd5f1d96..3c0c2395 100644
--- a/src/act-compat.js
+++ b/src/act-compat.js
@@ -28,19 +28,21 @@ function asyncAct(cb) {
         console.error = function error(...args) {
           /* if console.error fired *with that specific message* */
           /* istanbul ignore next */
-          if (
-            args[0].indexOf(
-              'Warning: Do not await the result of calling ReactTestUtils.act',
-            ) === 0
-          ) {
-            // v16.8.6
-            isAsyncActSupported = false
-          } else if (
-            args[0].indexOf(
-              'Warning: The callback passed to ReactTestUtils.act(...) function must not return anything',
-            ) === 0
-          ) {
-            // no-op
+          if (typeof args[0] === 'string') {
+            if (
+              args[0].indexOf(
+                'Warning: Do not await the result of calling ReactTestUtils.act',
+              ) === 0
+            ) {
+              // v16.8.6
+              isAsyncActSupported = false
+            } else if (
+              args[0].indexOf(
+                'Warning: The callback passed to ReactTestUtils.act(...) function must not return anything',
+              ) === 0
+            ) {
+              // no-op
+            }
           } else {
             originalConsoleError.apply(console, args)
           }