diff --git a/keyserver/src/fetchers/message-fetchers.js b/keyserver/src/fetchers/message-fetchers.js
--- a/keyserver/src/fetchers/message-fetchers.js
+++ b/keyserver/src/fetchers/message-fetchers.js
@@ -984,7 +984,7 @@
   inputQuery: string,
   threadID: string,
   viewer?: Viewer,
-  cursor?: string,
+  cursor?: ?string,
 ): Promise<SearchMessagesResponse> {
   if (inputQuery === '') {
     console.warn('received empty search query');
diff --git a/lib/shared/search-utils.js b/lib/shared/search-utils.js
--- a/lib/shared/search-utils.js
+++ b/lib/shared/search-utils.js
@@ -252,7 +252,7 @@
     threadID: string,
   ) => mixed,
   queryID: number,
-  cursor?: string,
+  cursor?: ?string,
 ) => void {
   const callSearchMessages = useSearchMessagesAction();
   const dispatchActionPromise = useDispatchActionPromise();
diff --git a/lib/types/message-types.js b/lib/types/message-types.js
--- a/lib/types/message-types.js
+++ b/lib/types/message-types.js
@@ -675,7 +675,7 @@
 export type SearchMessagesRequest = {
   +query: string,
   +threadID: string,
-  +cursor?: string,
+  +cursor?: ?string,
 };
 
 export type SearchMessagesResponse = {
diff --git a/native/search/message-search.react.js b/native/search/message-search.react.js
--- a/native/search/message-search.react.js
+++ b/native/search/message-search.react.js
@@ -47,7 +47,7 @@
     return props.navigation.addListener('beforeRemove', clearQuery);
   }, [props.navigation, clearQuery]);
 
-  const [lastID, setLastID] = React.useState();
+  const [lastID, setLastID] = React.useState<?string>();
   const [searchResults, setSearchResults] = React.useState<
     $ReadOnlyArray<RawMessageInfo>,
   >([]);