diff --git a/packages/preact-query/src/__tests__/fine-grained-persister.test.tsx b/packages/preact-query/src/__tests__/fine-grained-persister.test.tsx
index a4f7172b5c..6713e9c9f1 100644
--- a/packages/preact-query/src/__tests__/fine-grained-persister.test.tsx
+++ b/packages/preact-query/src/__tests__/fine-grained-persister.test.tsx
@@ -80,11 +80,7 @@ describe('fine grained persister', () => {
   it('should restore query state from persister and refetch', async () => {
     const key = queryKey()
     const hash = hashKey(key)
-    const spy = vi.fn(async () => {
-      await sleep(5)
-
-      return 'Works from queryFn'
-    })
+    const spy = vi.fn(() => sleep(5).then(() => 'Works from queryFn'))
 
     const mapStorage = new Map()
     const storage = {
diff --git a/packages/preact-query/src/__tests__/useMutation.test.tsx b/packages/preact-query/src/__tests__/useMutation.test.tsx
index 20da59ce50..f060c496f0 100644
--- a/packages/preact-query/src/__tests__/useMutation.test.tsx
+++ b/packages/preact-query/src/__tests__/useMutation.test.tsx
@@ -158,10 +158,9 @@ describe('useMutation', () => {
       return Promise.reject(new Error('Error test Jonas'))
     })
 
-    mutateFn.mockImplementation(async (value) => {
-      await sleep(10)
-      return Promise.resolve(value)
-    })
+    mutateFn.mockImplementation((value) =>
+      sleep(10).then(() => Promise.resolve(value)),
+    )
 
     function Page() {
       const { mutate, failureCount, failureReason, data, status } = useMutation(
@@ -370,10 +369,7 @@ describe('useMutation', () => {
     const key = queryKey()
 
     queryClient.setMutationDefaults(key, {
-      mutationFn: async (text: string) => {
-        await sleep(10)
-        return text
-      },
+      mutationFn: (text: string) => sleep(10).then(() => text),
     })
 
     const states: Array<UseMutationResult<any, any, any, any>> = []
@@ -1034,10 +1030,7 @@ describe('useMutation', () => {
 
     function Page() {
       const mutation = useMutation({
-        mutationFn: async (_text: string) => {
-          await sleep(10)
-          return 'result'
-        },
+        mutationFn: (_text: string) => sleep(10).then(() => 'result'),
         onSuccess: () => Promise.reject(error),
         onError,
       })
diff --git a/packages/preact-query/src/__tests__/usePrefetchQuery.test.tsx b/packages/preact-query/src/__tests__/usePrefetchQuery.test.tsx
index 603d3f4b3e..a7cc0253a3 100644
--- a/packages/preact-query/src/__tests__/usePrefetchQuery.test.tsx
+++ b/packages/preact-query/src/__tests__/usePrefetchQuery.test.tsx
@@ -18,11 +18,7 @@ import { renderWithClient } from './utils'
 const generateQueryFn = (data: string) =>
   vi
     .fn<(...args: Array<any>) => Promise<string>>()
-    .mockImplementation(async () => {
-      await sleep(10)
-
-      return data
-    })
+    .mockImplementation(() => sleep(10).then(() => data))
 
 describe('usePrefetchQuery', () => {
   let queryCache: QueryCache
diff --git a/packages/preact-query/src/__tests__/useQueries.test.tsx b/packages/preact-query/src/__tests__/useQueries.test.tsx
index 83bc5785d8..4a59b4e338 100644
--- a/packages/preact-query/src/__tests__/useQueries.test.tsx
+++ b/packages/preact-query/src/__tests__/useQueries.test.tsx
@@ -55,17 +55,11 @@ describe('useQueries', () => {
         queries: [
           {
             queryKey: key1,
-            queryFn: async () => {
-              await sleep(10)
-              return 1
-            },
+            queryFn: () => sleep(10).then(() => 1),
           },
           {
             queryKey: key2,
-            queryFn: async () => {
-              await sleep(200)
-              return 2
-            },
+            queryFn: () => sleep(200).then(() => 2),
           },
         ],
       })
@@ -1094,17 +1088,11 @@ describe('useQueries', () => {
         queries: [
           {
             queryKey: key1,
-            queryFn: async () => {
-              await sleep(5)
-              return Promise.resolve('query1')
-            },
+            queryFn: () => sleep(5).then(() => Promise.resolve('query1')),
           },
           {
             queryKey: key2,
-            queryFn: async () => {
-              await sleep(20)
-              return Promise.resolve('query2')
-            },
+            queryFn: () => sleep(20).then(() => Promise.resolve('query2')),
           },
         ],
         combine: ([query1, query2]) => {
@@ -1139,17 +1127,13 @@ describe('useQueries', () => {
           queries: [
             {
               queryKey: key1,
-              queryFn: async () => {
-                await sleep(5)
-                return Promise.resolve(`first result ${count}`)
-              },
+              queryFn: () =>
+                sleep(5).then(() => Promise.resolve(`first result ${count}`)),
             },
             {
               queryKey: key2,
-              queryFn: async () => {
-                await sleep(50)
-                return Promise.resolve(`second result ${count}`)
-              },
+              queryFn: () =>
+                sleep(50).then(() => Promise.resolve(`second result ${count}`)),
             },
           ],
           combine: (queryResults) => {
@@ -1331,17 +1315,11 @@ describe('useQueries', () => {
           queries: [
             {
               queryKey: key1,
-              queryFn: async () => {
-                await sleep(10)
-                return `first result:${value}`
-              },
+              queryFn: () => sleep(10).then(() => `first result:${value}`),
             },
             {
               queryKey: key2,
-              queryFn: async () => {
-                await sleep(20)
-                return `second result:${value}`
-              },
+              queryFn: () => sleep(20).then(() => `second result:${value}`),
             },
           ],
           combine: useCallback((results: Array<QueryObserverResult>) => {
@@ -1415,17 +1393,11 @@ describe('useQueries', () => {
           queries: [
             {
               queryKey: [key1],
-              queryFn: async () => {
-                await sleep(10)
-                return 'first result'
-              },
+              queryFn: () => sleep(10).then(() => 'first result'),
             },
             {
               queryKey: [key2],
-              queryFn: async () => {
-                await sleep(20)
-                return 'second result'
-              },
+              queryFn: () => sleep(20).then(() => 'second result'),
             },
           ],
           combine: useCallback(
@@ -1539,24 +1511,15 @@ describe('useQueries', () => {
           queries: [
             {
               queryKey: [key1],
-              queryFn: async () => {
-                await sleep(10)
-                return 'first result'
-              },
+              queryFn: () => sleep(10).then(() => 'first result'),
             },
             {
               queryKey: [key2],
-              queryFn: async () => {
-                await sleep(15)
-                return 'second result'
-              },
+              queryFn: () => sleep(15).then(() => 'second result'),
             },
             {
               queryKey: [key3],
-              queryFn: async () => {
-                await sleep(20)
-                return 'third result'
-              },
+              queryFn: () => sleep(20).then(() => 'third result'),
             },
           ],
           combine: (results) => {
@@ -1601,24 +1564,15 @@ describe('useQueries', () => {
           queries: [
             {
               queryKey: [key1],
-              queryFn: async () => {
-                await sleep(10)
-                return 'first result'
-              },
+              queryFn: () => sleep(10).then(() => 'first result'),
             },
             {
               queryKey: [key2],
-              queryFn: async () => {
-                await sleep(15)
-                return 'second result'
-              },
+              queryFn: () => sleep(15).then(() => 'second result'),
             },
             {
               queryKey: [key3],
-              queryFn: async () => {
-                await sleep(20)
-                return 'third result'
-              },
+              queryFn: () => sleep(20).then(() => 'third result'),
             },
           ],
           combine: (results) => {
@@ -1680,17 +1634,11 @@ describe('useQueries', () => {
           queries: [
             {
               queryKey: key1,
-              queryFn: async () => {
-                await sleep(10)
-                return 'first result'
-              },
+              queryFn: () => sleep(10).then(() => 'first result'),
             },
             {
               queryKey: key2,
-              queryFn: async () => {
-                await sleep(20)
-                return 'second result'
-              },
+              queryFn: () => sleep(20).then(() => 'second result'),
             },
           ],
           combine: useCallback((results: Array<QueryObserverResult>) => {
diff --git a/packages/preact-query/src/__tests__/useQuery.test.tsx b/packages/preact-query/src/__tests__/useQuery.test.tsx
index b03b9edea2..ed569d5293 100644
--- a/packages/preact-query/src/__tests__/useQuery.test.tsx
+++ b/packages/preact-query/src/__tests__/useQuery.test.tsx
@@ -83,10 +83,7 @@ describe('useQuery', () => {
     function Page() {
       const state = useQuery<string, Error>({
         queryKey: key,
-        queryFn: async () => {
-          await sleep(10)
-          return 'test'
-        },
+        queryFn: () => sleep(10).then(() => 'test'),
       })
 
       states.push(state)
@@ -472,10 +469,7 @@ describe('useQuery', () => {
     function Component({ value }: { value: string }) {
       const state = useQuery({
         queryKey: key,
-        queryFn: async () => {
-          await sleep(10)
-          return `data: ${value}`
-        },
+        queryFn: () => sleep(10).then(() => `data: ${value}`),
 
         gcTime: 0,
         notifyOnChangeProps: 'all',
@@ -534,10 +528,7 @@ describe('useQuery', () => {
 
       const state = useQuery({
         queryKey: key,
-        queryFn: async () => {
-          await sleep(5)
-          return 'data'
-        },
+        queryFn: () => sleep(5).then(() => 'data'),
 
         gcTime: 0,
         notifyOnChangeProps: ['isPending', 'isSuccess', 'data'],
@@ -1003,10 +994,7 @@ describe('useQuery', () => {
     function Page() {
       const result = useQuery({
         queryKey: key,
-        queryFn: async () => {
-          await sleep(10)
-          return 'fetched'
-        },
+        queryFn: () => sleep(10).then(() => 'fetched'),
 
         initialData: 'initial',
         staleTime: Infinity,
@@ -1164,10 +1152,7 @@ describe('useQuery', () => {
 
       const state = useQuery({
         queryKey: [key, count],
-        queryFn: async () => {
-          await sleep(5)
-          return count
-        },
+        queryFn: () => sleep(5).then(() => count),
         enabled: count === 0,
       })
 
@@ -1224,10 +1209,7 @@ describe('useQuery', () => {
 
       const state = useQuery({
         queryKey: [key, count],
-        queryFn: async () => {
-          await sleep(10)
-          return count
-        },
+        queryFn: () => sleep(10).then(() => count),
         placeholderData: keepPreviousData,
       })
 
@@ -1594,10 +1576,7 @@ describe('useQuery', () => {
 
       const state = useQuery({
         queryKey: [key, count],
-        queryFn: async () => {
-          await sleep(10)
-          return count
-        },
+        queryFn: () => sleep(10).then(() => count),
         initialData: 99,
         placeholderData: keepPreviousData,
       })
@@ -1666,10 +1645,7 @@ describe('useQuery', () => {
 
       const state = useQuery({
         queryKey: [key, count],
-        queryFn: async () => {
-          await sleep(10)
-          return count
-        },
+        queryFn: () => sleep(10).then(() => count),
         enabled: false,
         placeholderData: keepPreviousData,
         notifyOnChangeProps: 'all',
@@ -1764,10 +1740,7 @@ describe('useQuery', () => {
 
       const state = useQuery({
         queryKey: [key, count],
-        queryFn: async () => {
-          await sleep(10)
-          return count
-        },
+        queryFn: () => sleep(10).then(() => count),
         enabled: false,
         placeholderData: keepPreviousData,
         notifyOnChangeProps: 'all',
@@ -1842,10 +1815,7 @@ describe('useQuery', () => {
     function FirstComponent() {
       const state = useQuery({
         queryKey: key,
-        queryFn: async () => {
-          await sleep(10)
-          return 1
-        },
+        queryFn: () => sleep(10).then(() => 1),
         notifyOnChangeProps: 'all',
       })
       const refetch = state.refetch
@@ -1905,10 +1875,7 @@ describe('useQuery', () => {
 
     queryClient.prefetchQuery({
       queryKey: key,
-      queryFn: async () => {
-        await sleep(10)
-        return 'prefetch'
-      },
+      queryFn: () => sleep(10).then(() => 'prefetch'),
     })
 
     await vi.advanceTimersByTimeAsync(20)
@@ -1916,10 +1883,7 @@ describe('useQuery', () => {
     function FirstComponent() {
       const state = useQuery({
         queryKey: key,
-        queryFn: async () => {
-          await sleep(10)
-          return 'one'
-        },
+        queryFn: () => sleep(10).then(() => 'one'),
 
         staleTime: 100,
       })
@@ -1930,10 +1894,7 @@ describe('useQuery', () => {
     function SecondComponent() {
       const state = useQuery({
         queryKey: key,
-        queryFn: async () => {
-          await sleep(10)
-          return 'two'
-        },
+        queryFn: () => sleep(10).then(() => 'two'),
 
         staleTime: 10,
       })
@@ -2035,10 +1996,7 @@ describe('useQuery', () => {
     }) => {
       return useQuery({
         queryKey: [key, id],
-        queryFn: async () => {
-          await sleep(10)
-          return { id, name: 'John' }
-        },
+        queryFn: () => sleep(10).then(() => ({ id, name: 'John' })),
         enabled: !!id && enabled,
       })
     }
@@ -2132,10 +2090,7 @@ describe('useQuery', () => {
       function Page() {
         const state = useQuery({
           queryKey: key,
-          queryFn: async () => {
-            await sleep(5)
-            return 'test'
-          },
+          queryFn: () => sleep(5).then(() => 'test'),
 
           notifyOnChangeProps: ['data'],
         })
@@ -2189,10 +2144,7 @@ describe('useQuery', () => {
         function Page() {
           const state = useQuery({
             queryKey: key,
-            queryFn: async () => {
-              await sleep(5)
-              return 'test'
-            },
+            queryFn: () => sleep(5).then(() => 'test'),
             notifyOnChangeProps: () => ['data'],
           })
 
@@ -2380,10 +2332,7 @@ describe('useQuery', () => {
   it('should update query options', () => {
     const key = queryKey()
 
-    const queryFn = async () => {
-      await sleep(10)
-      return 'data1'
-    }
+    const queryFn = () => sleep(10).then(() => 'data1')
 
     function Page() {
       useQuery({ queryKey: key, queryFn, retryDelay: 10 })
@@ -2401,10 +2350,7 @@ describe('useQuery', () => {
 
     let renders = 0
 
-    const queryFn = async () => {
-      await sleep(15)
-      return 'data'
-    }
+    const queryFn = () => sleep(15).then(() => 'data')
 
     function Page() {
       const query1 = useQuery({ queryKey: key, queryFn })
@@ -2457,18 +2403,12 @@ describe('useQuery', () => {
     function Page() {
       const first = useQuery({
         queryKey: key1,
-        queryFn: async () => {
-          await sleep(10)
-          return 'data'
-        },
+        queryFn: () => sleep(10).then(() => 'data'),
         enabled: false,
       })
       const second = useQuery({
         queryKey: key2,
-        queryFn: async () => {
-          await sleep(10)
-          return 'data'
-        },
+        queryFn: () => sleep(10).then(() => 'data'),
       })
 
       return (
@@ -2507,10 +2447,7 @@ describe('useQuery', () => {
     function Page() {
       const { status } = useQuery({
         queryKey: key,
-        queryFn: async () => {
-          await sleep(10)
-          return 'test'
-        },
+        queryFn: () => sleep(10).then(() => 'test'),
       })
 
       return <div>status: {status}</div>
@@ -3555,10 +3492,7 @@ describe('useQuery', () => {
     function Page() {
       const state = useQuery({
         queryKey: key,
-        queryFn: async () => {
-          await sleep(10)
-          return 'data'
-        },
+        queryFn: () => sleep(10).then(() => 'data'),
       })
       states.push(state)
       return (
@@ -3648,10 +3582,7 @@ describe('useQuery', () => {
 
     const prefetchQueryFn =
       vi.fn<(...args: Array<unknown>) => Promise<string>>()
-    prefetchQueryFn.mockImplementation(async () => {
-      await sleep(10)
-      return 'not yet...'
-    })
+    prefetchQueryFn.mockImplementation(() => sleep(10).then(() => 'not yet...'))
 
     queryClient.prefetchQuery({
       queryKey: key,
@@ -3771,10 +3702,7 @@ describe('useQuery', () => {
 
       const query = useQuery({
         queryKey: key,
-        queryFn: async () => {
-          await sleep(10)
-          return 'data'
-        },
+        queryFn: () => sleep(10).then(() => 'data'),
         enabled: shouldFetch,
       })
 
@@ -3810,10 +3738,7 @@ describe('useQuery', () => {
     function Page() {
       const result = useQuery({
         queryKey: key,
-        queryFn: async () => {
-          await sleep(10)
-          return 'serverData'
-        },
+        queryFn: () => sleep(10).then(() => 'serverData'),
         initialData: 'initialData',
       })
       results.push(result)
@@ -4504,10 +4429,7 @@ describe('useQuery', () => {
 
       const state = useQuery({
         queryKey: key1,
-        queryFn: async () => {
-          await sleep(10)
-          return 0
-        },
+        queryFn: () => sleep(10).then(() => 0),
         select: useCallback(
           (data: number) => {
             selectRun++
@@ -4550,10 +4472,7 @@ describe('useQuery', () => {
 
       const state = useQuery({
         queryKey: key1,
-        queryFn: async () => {
-          await sleep(10)
-          return 0
-        },
+        queryFn: () => sleep(10).then(() => 0),
 
         select: useCallback(
           (data: number) => {
@@ -4603,10 +4522,7 @@ describe('useQuery', () => {
 
       const state = useQuery({
         queryKey: key1,
-        queryFn: async () => {
-          await sleep(10)
-          return [1, 2]
-        },
+        queryFn: () => sleep(10).then(() => [1, 2]),
 
         select: (res) => res.map((x) => x + 1),
       })
@@ -4747,10 +4663,7 @@ describe('useQuery', () => {
     const key = queryKey()
     const states: Array<UseQueryResult<string>> = []
 
-    const queryFn = async () => {
-      await sleep(50)
-      return 'OK'
-    }
+    const queryFn = () => sleep(50).then(() => 'OK')
 
     function Page() {
       const [id, setId] = useState(1)
@@ -4995,10 +4908,9 @@ describe('useQuery', () => {
 
   it('should refetch when changed enabled to true in error state', async () => {
     const queryFn = vi.fn<(...args: Array<unknown>) => unknown>()
-    queryFn.mockImplementation(async () => {
-      await sleep(10)
-      return Promise.reject(new Error('Suspense Error Bingo'))
-    })
+    queryFn.mockImplementation(() =>
+      sleep(10).then(() => Promise.reject(new Error('Suspense Error Bingo'))),
+    )
 
     function Page({ enabled }: { enabled: boolean }) {
       const { error, isPending } = useQuery({
@@ -5117,10 +5029,8 @@ describe('useQuery', () => {
     function Page({ id }: { id: boolean }) {
       const { error, isFetching } = useQuery({
         queryKey: [id],
-        queryFn: async () => {
-          await sleep(10)
-          return Promise.reject<unknown>(new Error('Error'))
-        },
+        queryFn: () =>
+          sleep(10).then(() => Promise.reject<unknown>(new Error('Error'))),
         retry: false,
         retryOnMount: false,
         refetchOnMount: false,
@@ -5254,10 +5164,7 @@ describe('useQuery', () => {
       function Page() {
         const state = useQuery({
           queryKey: key,
-          queryFn: async () => {
-            await sleep(10)
-            return 'data'
-          },
+          queryFn: () => sleep(10).then(() => 'data'),
         })
 
         useEffect(() => {
@@ -6220,10 +6127,7 @@ describe('useQuery', () => {
       const { data, status } = useQuery({
         enabled: false,
         queryKey: key,
-        queryFn: async () => {
-          await sleep(10)
-          return 5
-        },
+        queryFn: () => sleep(10).then(() => 5),
       })
 
       const mounted = useRef<boolean>(null)
@@ -6389,10 +6293,7 @@ describe('useQuery', () => {
 
       const { data } = useQuery({
         queryKey: [key],
-        queryFn: async () => {
-          await sleep(5)
-          return 'Works'
-        },
+        queryFn: () => sleep(5).then(() => 'Works'),
       })
 
       return <div ref={(value) => setRef(value)}>{data}</div>
@@ -6415,10 +6316,7 @@ describe('useQuery', () => {
       const state = useQuery({
         staleTime: Infinity,
         queryKey: [key, steps[count]],
-        queryFn: async () => {
-          await sleep(10)
-          return steps[count]
-        },
+        queryFn: () => sleep(10).then(() => steps[count]),
         placeholderData: keepPreviousData,
       })
 
@@ -6531,11 +6429,7 @@ describe('useQuery', () => {
       const { data, status } = useQuery({
         queryKey: [key],
         queryFn: enabled
-          ? async () => {
-              await sleep(10)
-
-              return Promise.resolve('data')
-            }
+          ? () => sleep(10).then(() => Promise.resolve('data'))
           : skipToken,
         retry: false,
         retryOnMount: false,
@@ -6612,10 +6506,7 @@ describe('useQuery', () => {
     function Page() {
       const query = useQuery({
         queryKey: key,
-        queryFn: async () => {
-          await sleep(10)
-          return Promise.reject(error)
-        },
+        queryFn: () => sleep(10).then(() => Promise.reject(error)),
         retry: false,
         notifyOnChangeProps: 'all',
       })
@@ -6714,10 +6605,7 @@ describe('useQuery', () => {
 
     void serverQueryClient.prefetchQuery({
       queryKey: key,
-      queryFn: async () => {
-        await sleep(10)
-        return Promise.resolve('server')
-      },
+      queryFn: () => sleep(10).then(() => Promise.resolve('server')),
     })
 
     const dehydrated = dehydrate(serverQueryClient)
@@ -6772,10 +6660,8 @@ describe('useQuery', () => {
 
     void serverQueryClient.prefetchQuery({
       queryKey: key,
-      queryFn: async () => {
-        await sleep(10)
-        return Promise.reject(new Error('server error'))
-      },
+      queryFn: () =>
+        sleep(10).then(() => Promise.reject(new Error('server error'))),
     })
 
     const dehydrated = dehydrate(serverQueryClient)
diff --git a/packages/preact-query/src/__tests__/useSuspenseQueries.test.tsx b/packages/preact-query/src/__tests__/useSuspenseQueries.test.tsx
index 9968d2db5e..bc8df24020 100644
--- a/packages/preact-query/src/__tests__/useSuspenseQueries.test.tsx
+++ b/packages/preact-query/src/__tests__/useSuspenseQueries.test.tsx
@@ -291,10 +291,8 @@ describe('useSuspenseQueries', () => {
     function getUserData() {
       return {
         queryKey: key,
-        queryFn: async () => {
-          await sleep(localDuration)
-          return { name: 'John Doe', age: 50 }
-        },
+        queryFn: () =>
+          sleep(localDuration).then(() => ({ name: 'John Doe', age: 50 })),
       }
     }