diff --git a/keyserver/src/creators/upload-creator.js b/keyserver/src/creators/upload-creator.js
--- a/keyserver/src/creators/upload-creator.js
+++ b/keyserver/src/creators/upload-creator.js
@@ -22,6 +22,7 @@
   buffer: Buffer,
   dimensions: Dimensions,
   loop: boolean,
+  thread: string,
 };
 async function createUploads(
   viewer: Viewer,
@@ -35,10 +36,11 @@
   const uploadRows = uploadInfos.map(uploadInfo => {
     const id = ids.shift();
     const secret = crypto.randomBytes(8).toString('hex');
-    const { dimensions, mediaType, loop } = uploadInfo;
+    const { dimensions, mediaType, loop, thread } = uploadInfo;
     return {
       uploadResult: {
         id,
+        thread,
         uri: shimUploadURI(getUploadURL(id, secret), viewer.platformDetails),
         dimensions,
         mediaType,
@@ -46,6 +48,7 @@
       },
       insert: [
         id,
+        thread,
         viewer.userID,
         mediaType,
         uploadInfo.name,
@@ -59,7 +62,7 @@
   });
 
   const insertQuery = SQL`
-    INSERT INTO uploads(id, uploader, type, filename,
+    INSERT INTO uploads(id, thread, uploader, type, filename,
       mime, content, secret, creation_time, extra)
     VALUES ${uploadRows.map(({ insert }) => insert)}
   `;
diff --git a/keyserver/src/uploads/media-utils.js b/keyserver/src/uploads/media-utils.js
--- a/keyserver/src/uploads/media-utils.js
+++ b/keyserver/src/uploads/media-utils.js
@@ -35,6 +35,7 @@
   inputDimensions: ?Dimensions,
   inputLoop: boolean,
   size: number, // in bytes
+  thread: string,
 ): Promise<?UploadInput> {
   const { mime, mediaType } = deepFileInfoFromData(initialBuffer);
   if (!mime || !mediaType) {
@@ -57,6 +58,7 @@
       buffer: initialBuffer,
       dimensions: inputDimensions,
       loop: inputLoop,
+      thread: thread,
     };
   }
 
@@ -72,6 +74,7 @@
     inputDimensions,
     inputLoop,
     size,
+    thread,
   );
 }
 
@@ -82,6 +85,7 @@
   inputDimensions: ?Dimensions,
   inputLoop: boolean,
   size: number,
+  thread: string,
 ): Promise<?UploadInput> {
   let sharpImage, metadata;
   try {
@@ -116,6 +120,7 @@
       buffer: initialBuffer,
       dimensions: initialDimensions,
       loop: inputLoop,
+      thread,
     };
   }
   console.log(`processing image with ${JSON.stringify(plan)}`);
@@ -168,6 +173,7 @@
     buffer: convertedBuffer,
     dimensions: convertedDimensions,
     loop: inputLoop,
+    thread,
   };
 }
 
diff --git a/keyserver/src/uploads/uploads.js b/keyserver/src/uploads/uploads.js
--- a/keyserver/src/uploads/uploads.js
+++ b/keyserver/src/uploads/uploads.js
@@ -57,6 +57,11 @@
 
   const inputLoop = !!(files.length === 1 && body.loop);
 
+  let thread;
+  if (files.length === 1 && typeof body.thread === 'string') {
+    thread = body.thread;
+  }
+
   const validationResults = await Promise.all(
     files.map(({ buffer, size, originalname }) =>
       validateAndConvert(
@@ -65,6 +70,7 @@
         inputDimensions,
         inputLoop,
         size,
+        thread,
       ),
     ),
   );
diff --git a/lib/actions/upload-actions.js b/lib/actions/upload-actions.js
--- a/lib/actions/upload-actions.js
+++ b/lib/actions/upload-actions.js
@@ -10,7 +10,11 @@
   abortHandler: (abort: () => void) => void,
   uploadBlob: UploadBlob,
 }>;
-export type MultimediaUploadExtras = Shape<{ ...Dimensions, loop: boolean }>;
+export type MultimediaUploadExtras = Shape<{
+  thread: string,
+  ...Dimensions,
+  loop: boolean,
+}>;
 
 const uploadMultimedia = (
   callServerEndpoint: CallServerEndpoint,
@@ -28,6 +32,9 @@
   const uploadBlob = callbacks && callbacks.uploadBlob;
 
   const stringExtras = {};
+  if (extras.thread !== null && extras.thread !== undefined) {
+    stringExtras.thread = extras.thread.toString();
+  }
   if (extras.height !== null && extras.height !== undefined) {
     stringExtras.height = extras.height.toString();
   }
@@ -57,6 +64,7 @@
     dimensions: uploadResult.dimensions,
     mediaType: uploadResult.mediaType,
     loop: uploadResult.loop,
+    thread: uploadResult.thread,
   };
 };
 
diff --git a/lib/types/media-types.js b/lib/types/media-types.js
--- a/lib/types/media-types.js
+++ b/lib/types/media-types.js
@@ -65,6 +65,7 @@
   +dimensions: Dimensions,
   +mediaType: MediaType,
   +loop: boolean,
+  +thread: string,
 };
 
 export type UpdateMultimediaMessageMediaPayload = {
diff --git a/native/input/input-state-container.react.js b/native/input/input-state-container.react.js
--- a/native/input/input-state-container.react.js
+++ b/native/input/input-state-container.react.js
@@ -569,16 +569,17 @@
       },
     );
 
-    await this.uploadFiles(localMessageID, uploadFileInputs);
+    await this.uploadFiles(localMessageID, threadInfo.id, uploadFileInputs);
   };
 
   async uploadFiles(
     localMessageID: string,
+    threadID: string,
     uploadFileInputs: $ReadOnlyArray<UploadFileInput>,
   ) {
     const results = await Promise.all(
       uploadFileInputs.map(uploadFileInput =>
-        this.uploadFile(localMessageID, uploadFileInput),
+        this.uploadFile(localMessageID, threadID, uploadFileInput),
       ),
     );
     const errors = [...new Set(results.filter(Boolean))];
@@ -589,6 +590,7 @@
 
   async uploadFile(
     localMessageID: string,
+    threadID: string,
     uploadFileInput: UploadFileInput,
   ): Promise<?string> {
     const { ids, selection } = uploadFileInput;
@@ -665,6 +667,7 @@
         this.props.uploadMultimedia(
           { uri: uploadURI, name: filename, type: mime },
           {
+            thread: threadID,
             ...processedMedia.dimensions,
             loop:
               processedMedia.mediaType === 'video'
@@ -693,6 +696,7 @@
               type: 'image/jpeg',
             },
             {
+              thread: threadID,
               ...processedMedia.dimensions,
               loop: false,
             },
@@ -1266,7 +1270,7 @@
       };
     });
 
-    await this.uploadFiles(localMessageID, uploadFileInputs);
+    await this.uploadFiles(localMessageID, threadInfo.id, uploadFileInputs);
   };
 
   retryMessage = async (localMessageID: string, threadInfo: ThreadInfo) => {