diff --git a/packages/query-codemods/src/v4/__testfixtures__/default-import.input.tsx b/packages/query-codemods/src/v4/__testfixtures__/default-import.input.tsx
index 23c1c4c4907..85cadec144e 100644
--- a/packages/query-codemods/src/v4/__testfixtures__/default-import.input.tsx
+++ b/packages/query-codemods/src/v4/__testfixtures__/default-import.input.tsx
@@ -27,10 +27,10 @@ export const Examples = () => {
   queryClient.getQueryDefaults('todos')
   queryClient.getQueryState('todos')
   queryClient.isFetching('todos')
-  queryClient.setMutationDefaults('todos', { mutationFn: async () => null })
+  queryClient.setMutationDefaults('todos', { mutationFn: () => Promise.resolve(null) })
   queryClient.setQueriesData('todos', () => null)
   queryClient.setQueryData('todos', () => null)
-  queryClient.setQueryDefaults('todos', { queryFn: async () => null })
+  queryClient.setQueryDefaults('todos', { queryFn: () => Promise.resolve(null) })
   queryClient.cancelQueries('todos')
   queryClient.fetchInfiniteQuery('todos')
   queryClient.fetchQuery('todos')
@@ -48,11 +48,11 @@ export const Examples = () => {
   useQueryClient().getQueryState('todos')
   useQueryClient().isFetching('todos')
   useQueryClient().setMutationDefaults('todos', {
-    mutationFn: async () => null,
+    mutationFn: () => Promise.resolve(null),
   })
   useQueryClient().setQueriesData('todos', () => null)
   useQueryClient().setQueryData('todos', () => null)
-  useQueryClient().setQueryDefaults('todos', { queryFn: async () => null })
+  useQueryClient().setQueryDefaults('todos', { queryFn: () => Promise.resolve(null) })
   useQueryClient().cancelQueries('todos')
   useQueryClient().fetchInfiniteQuery('todos')
   useQueryClient().fetchQuery('todos')
diff --git a/packages/query-codemods/src/v4/__testfixtures__/default-import.output.tsx b/packages/query-codemods/src/v4/__testfixtures__/default-import.output.tsx
index 56cee683862..a0360586386 100644
--- a/packages/query-codemods/src/v4/__testfixtures__/default-import.output.tsx
+++ b/packages/query-codemods/src/v4/__testfixtures__/default-import.output.tsx
@@ -29,10 +29,10 @@ export const Examples = () => {
   queryClient.getQueryDefaults(['todos'])
   queryClient.getQueryState(['todos'])
   queryClient.isFetching(['todos'])
-  queryClient.setMutationDefaults(['todos'], { mutationFn: async () => null })
+  queryClient.setMutationDefaults(['todos'], { mutationFn: () => Promise.resolve(null) })
   queryClient.setQueriesData(['todos'], () => null)
   queryClient.setQueryData(['todos'], () => null)
-  queryClient.setQueryDefaults(['todos'], { queryFn: async () => null })
+  queryClient.setQueryDefaults(['todos'], { queryFn: () => Promise.resolve(null) })
   queryClient.cancelQueries(['todos'])
   queryClient.fetchInfiniteQuery(['todos'])
   queryClient.fetchQuery(['todos'])
@@ -50,11 +50,11 @@ export const Examples = () => {
   useQueryClient().getQueryState(['todos'])
   useQueryClient().isFetching(['todos'])
   useQueryClient().setMutationDefaults(['todos'], {
-    mutationFn: async () => null,
+    mutationFn: () => Promise.resolve(null),
   })
   useQueryClient().setQueriesData(['todos'], () => null)
   useQueryClient().setQueryData(['todos'], () => null)
-  useQueryClient().setQueryDefaults(['todos'], { queryFn: async () => null })
+  useQueryClient().setQueryDefaults(['todos'], { queryFn: () => Promise.resolve(null) })
   useQueryClient().cancelQueries(['todos'])
   useQueryClient().fetchInfiniteQuery(['todos'])
   useQueryClient().fetchQuery(['todos'])
diff --git a/packages/query-codemods/src/v4/__testfixtures__/named-import.input.tsx b/packages/query-codemods/src/v4/__testfixtures__/named-import.input.tsx
index 2d8d5947627..f50a89a740a 100644
--- a/packages/query-codemods/src/v4/__testfixtures__/named-import.input.tsx
+++ b/packages/query-codemods/src/v4/__testfixtures__/named-import.input.tsx
@@ -27,10 +27,10 @@ export const Examples = () => {
   queryClient.getQueryDefaults('todos')
   queryClient.getQueryState('todos')
   queryClient.isFetching('todos')
-  queryClient.setMutationDefaults('todos', { mutationFn: async () => null })
+  queryClient.setMutationDefaults('todos', { mutationFn: () => Promise.resolve(null) })
   queryClient.setQueriesData('todos', () => null)
   queryClient.setQueryData('todos', () => null)
-  queryClient.setQueryDefaults('todos', { queryFn: async () => null })
+  queryClient.setQueryDefaults('todos', { queryFn: () => Promise.resolve(null) })
   queryClient.cancelQueries('todos')
   queryClient.fetchInfiniteQuery('todos')
   queryClient.fetchQuery('todos')
@@ -48,12 +48,12 @@ export const Examples = () => {
   useRenamedQueryClient().getQueryState('todos')
   useRenamedQueryClient().isFetching('todos')
   useRenamedQueryClient().setMutationDefaults('todos', {
-    mutationFn: async () => null,
+    mutationFn: () => Promise.resolve(null),
   })
   useRenamedQueryClient().setQueriesData('todos', () => null)
   useRenamedQueryClient().setQueryData('todos', () => null)
   useRenamedQueryClient().setQueryDefaults('todos', {
-    queryFn: async () => null,
+    queryFn: () => Promise.resolve(null),
   })
   useRenamedQueryClient().cancelQueries('todos')
   useRenamedQueryClient().fetchInfiniteQuery('todos')
diff --git a/packages/query-codemods/src/v4/__testfixtures__/named-import.output.tsx b/packages/query-codemods/src/v4/__testfixtures__/named-import.output.tsx
index 716f56be068..90464063795 100644
--- a/packages/query-codemods/src/v4/__testfixtures__/named-import.output.tsx
+++ b/packages/query-codemods/src/v4/__testfixtures__/named-import.output.tsx
@@ -29,10 +29,10 @@ export const Examples = () => {
   queryClient.getQueryDefaults(['todos'])
   queryClient.getQueryState(['todos'])
   queryClient.isFetching(['todos'])
-  queryClient.setMutationDefaults(['todos'], { mutationFn: async () => null })
+  queryClient.setMutationDefaults(['todos'], { mutationFn: () => Promise.resolve(null) })
   queryClient.setQueriesData(['todos'], () => null)
   queryClient.setQueryData(['todos'], () => null)
-  queryClient.setQueryDefaults(['todos'], { queryFn: async () => null })
+  queryClient.setQueryDefaults(['todos'], { queryFn: () => Promise.resolve(null) })
   queryClient.cancelQueries(['todos'])
   queryClient.fetchInfiniteQuery(['todos'])
   queryClient.fetchQuery(['todos'])
@@ -50,12 +50,12 @@ export const Examples = () => {
   useRenamedQueryClient().getQueryState(['todos'])
   useRenamedQueryClient().isFetching(['todos'])
   useRenamedQueryClient().setMutationDefaults(['todos'], {
-    mutationFn: async () => null,
+    mutationFn: () => Promise.resolve(null),
   })
   useRenamedQueryClient().setQueriesData(['todos'], () => null)
   useRenamedQueryClient().setQueryData(['todos'], () => null)
   useRenamedQueryClient().setQueryDefaults(['todos'], {
-    queryFn: async () => null,
+    queryFn: () => Promise.resolve(null),
   })
   useRenamedQueryClient().cancelQueries(['todos'])
   useRenamedQueryClient().fetchInfiniteQuery(['todos'])
diff --git a/packages/query-codemods/src/v4/__testfixtures__/namespaced-import.input.tsx b/packages/query-codemods/src/v4/__testfixtures__/namespaced-import.input.tsx
index 95d2b282ace..e6bed4a022a 100644
--- a/packages/query-codemods/src/v4/__testfixtures__/namespaced-import.input.tsx
+++ b/packages/query-codemods/src/v4/__testfixtures__/namespaced-import.input.tsx
@@ -17,10 +17,10 @@ export const Examples = () => {
   queryClient.getQueryDefaults('todos')
   queryClient.getQueryState('todos')
   queryClient.isFetching('todos')
-  queryClient.setMutationDefaults('todos', { mutationFn: async () => null })
+  queryClient.setMutationDefaults('todos', { mutationFn: () => Promise.resolve(null) })
   queryClient.setQueriesData('todos', () => null)
   queryClient.setQueryData('todos', () => null)
-  queryClient.setQueryDefaults('todos', { queryFn: async () => null })
+  queryClient.setQueryDefaults('todos', { queryFn: () => Promise.resolve(null) })
   queryClient.cancelQueries('todos')
   queryClient.fetchInfiniteQuery('todos')
   queryClient.fetchQuery('todos')
@@ -38,12 +38,12 @@ export const Examples = () => {
   RQ.useQueryClient().getQueryState('todos')
   RQ.useQueryClient().isFetching('todos')
   RQ.useQueryClient().setMutationDefaults('todos', {
-    mutationFn: async () => null,
+    mutationFn: () => Promise.resolve(null),
   })
   RQ.useQueryClient().setQueriesData('todos', () => null)
   RQ.useQueryClient().setQueryData('todos', () => null)
   RQ.useQueryClient().setQueryDefaults('todos', {
-    queryFn: async () => null,
+    queryFn: () => Promise.resolve(null),
   })
   RQ.useQueryClient().cancelQueries('todos')
   RQ.useQueryClient().fetchInfiniteQuery('todos')
diff --git a/packages/query-codemods/src/v4/__testfixtures__/namespaced-import.output.tsx b/packages/query-codemods/src/v4/__testfixtures__/namespaced-import.output.tsx
index b6b13f36cf4..402e1aca510 100644
--- a/packages/query-codemods/src/v4/__testfixtures__/namespaced-import.output.tsx
+++ b/packages/query-codemods/src/v4/__testfixtures__/namespaced-import.output.tsx
@@ -19,10 +19,10 @@ export const Examples = () => {
   queryClient.getQueryDefaults(['todos'])
   queryClient.getQueryState(['todos'])
   queryClient.isFetching(['todos'])
-  queryClient.setMutationDefaults(['todos'], { mutationFn: async () => null })
+  queryClient.setMutationDefaults(['todos'], { mutationFn: () => Promise.resolve(null) })
   queryClient.setQueriesData(['todos'], () => null)
   queryClient.setQueryData(['todos'], () => null)
-  queryClient.setQueryDefaults(['todos'], { queryFn: async () => null })
+  queryClient.setQueryDefaults(['todos'], { queryFn: () => Promise.resolve(null) })
   queryClient.cancelQueries(['todos'])
   queryClient.fetchInfiniteQuery(['todos'])
   queryClient.fetchQuery(['todos'])
@@ -40,12 +40,12 @@ export const Examples = () => {
   RQ.useQueryClient().getQueryState(['todos'])
   RQ.useQueryClient().isFetching(['todos'])
   RQ.useQueryClient().setMutationDefaults(['todos'], {
-    mutationFn: async () => null,
+    mutationFn: () => Promise.resolve(null),
   })
   RQ.useQueryClient().setQueriesData(['todos'], () => null)
   RQ.useQueryClient().setQueryData(['todos'], () => null)
   RQ.useQueryClient().setQueryDefaults(['todos'], {
-    queryFn: async () => null,
+    queryFn: () => Promise.resolve(null),
   })
   RQ.useQueryClient().cancelQueries(['todos'])
   RQ.useQueryClient().fetchInfiniteQuery(['todos'])
diff --git a/packages/query-codemods/src/v5/remove-overloads/__testfixtures__/bug-reports.input.tsx b/packages/query-codemods/src/v5/remove-overloads/__testfixtures__/bug-reports.input.tsx
index acbb685e350..d68c9bf1e91 100644
--- a/packages/query-codemods/src/v5/remove-overloads/__testfixtures__/bug-reports.input.tsx
+++ b/packages/query-codemods/src/v5/remove-overloads/__testfixtures__/bug-reports.input.tsx
@@ -21,7 +21,7 @@ export function useDetailsContainsIdentifierAsThirdArgument({ groupId }: { group
 export function useWhatever({ thing }: { thing: string }) {
   return useQuery(
     ['some-string', someVar],
-    async () => 'foo',
+    () => Promise.resolve('foo'),
     { enabled: Boolean(thing) },
   );
 }
diff --git a/packages/query-codemods/src/v5/remove-overloads/__testfixtures__/bug-reports.output.tsx b/packages/query-codemods/src/v5/remove-overloads/__testfixtures__/bug-reports.output.tsx
index 6f983be35f7..0670500d34a 100644
--- a/packages/query-codemods/src/v5/remove-overloads/__testfixtures__/bug-reports.output.tsx
+++ b/packages/query-codemods/src/v5/remove-overloads/__testfixtures__/bug-reports.output.tsx
@@ -27,7 +27,7 @@ export function useDetailsContainsIdentifierAsThirdArgument({ groupId }: { group
 export function useWhatever({ thing }: { thing: string }) {
   return useQuery({
     queryKey: ['some-string', someVar],
-    queryFn: async () => 'foo',
+    queryFn: () => Promise.resolve('foo'),
     enabled: Boolean(thing)
   });
 }