diff --git a/packages/canvas-rce/src/sidebar/actions/images.js b/packages/canvas-rce/src/sidebar/actions/images.js
index 26ba2ba436e..12cc8002f9d 100644
--- a/packages/canvas-rce/src/sidebar/actions/images.js
+++ b/packages/canvas-rce/src/sidebar/actions/images.js
@@ -47,8 +47,8 @@ export function requestImages(contextType) {
 }
 
 export function receiveImages({response, contextType}) {
-  const {files, bookmark} = response
-  return {type: RECEIVE_IMAGES, payload: {files, bookmark, contextType}}
+  const {files, bookmark, searchString} = response
+  return {type: RECEIVE_IMAGES, payload: {files, bookmark, contextType, searchString}}
 }
 
 export function failImagesLoad({error, contextType}) {
diff --git a/packages/canvas-rce/src/sidebar/reducers/images.js b/packages/canvas-rce/src/sidebar/reducers/images.js
index 71496cd0e72..af214621155 100644
--- a/packages/canvas-rce/src/sidebar/reducers/images.js
+++ b/packages/canvas-rce/src/sidebar/reducers/images.js
@@ -68,11 +68,16 @@ export default function imagesReducer(prevState = {}, action) {
       return state
 
     case RECEIVE_IMAGES:
-      state[ctxt] = {
-        files: state[ctxt].files.concat(action.payload.files),
-        isLoading: false,
-        bookmark: action.payload.bookmark,
-        hasMore: !!action.payload.bookmark
+      // If a request resolved with files but the searchString has since
+      // changed, then the files should not be concatenated because this
+      // request will have been redundant at best and wrong at worst.
+      if (action.payload.searchString === state.searchString) {
+        state[ctxt] = {
+          files: state[ctxt].files.concat(action.payload.files),
+          isLoading: false,
+          bookmark: action.payload.bookmark,
+          hasMore: !!action.payload.bookmark
+        }
       }
       return state
 
@@ -91,6 +96,7 @@ export default function imagesReducer(prevState = {}, action) {
     }
 
     case CHANGE_SEARCH_STRING: {
+      state.searchString = action.payload
       return state
     }
 
diff --git a/packages/canvas-rce/src/sidebar/sources/api.js b/packages/canvas-rce/src/sidebar/sources/api.js
index 8926ce3c37b..9bb1fbc7455 100644
--- a/packages/canvas-rce/src/sidebar/sources/api.js
+++ b/packages/canvas-rce/src/sidebar/sources/api.js
@@ -130,7 +130,8 @@ class RceApiSource {
         bookmark: null,
         isLoading: false,
         hasMore: true
-      }
+      },
+      searchString: ''
     }
   }
 
@@ -349,7 +350,8 @@ class RceApiSource {
     return this.apiFetch(uri, headers).then(({bookmark, files}) => {
       return {
         bookmark,
-        files: files.map(f => fixupFileUrl(props.contextType, props.contextId, f))
+        files: files.map(f => fixupFileUrl(props.contextType, props.contextId, f)),
+        searchString: props.searchString
       }
     })
   }
diff --git a/packages/canvas-rce/test/sidebar/actions/images.test.js b/packages/canvas-rce/test/sidebar/actions/images.test.js
index 6a0c1ffdaff..99e3b326c41 100644
--- a/packages/canvas-rce/test/sidebar/actions/images.test.js
+++ b/packages/canvas-rce/test/sidebar/actions/images.test.js
@@ -23,6 +23,44 @@ import * as actions from '../../../src/sidebar/actions/images'
 const sortBy = {sort: 'alphabetical', order: 'asc'}
 const searchString = 'hello'
 
+describe('Image dispatch shapes', () => {
+  describe('receiveImages', () => {
+    const contextType = 'course'
+    const response = {
+      bookmark: 'p2',
+      files: [],
+      searchString: 'panda'
+    }
+
+    it('returns a type of RECEIVE_IMAGES', () => {
+      const {type} = actions.receiveImages()
+      assert(type === actions.RECEIVE_IMAGES)
+    })
+
+    describe('returning a payload', () => {
+      it('includes contextType', () => {
+        const {payload} = actions.receiveImages({response, contextType})
+        assert(payload.contextType === 'course')
+      })
+
+      it('includes files', () => {
+        const {payload} = actions.receiveImages({response})
+        assert(payload.files === [])
+      })
+
+      it('includes bookmark', () => {
+        const {payload} = actions.receiveImages({response})
+        assert(payload.bookmark === 'p2')
+      })
+
+      it('includes searchString', () => {
+        const {payload} = actions.receiveImages({response})
+        assert(payload.searchString === 'panda')
+      })
+    })
+  })
+})
+
 describe('Image actions', () => {
   describe('createAddImage', () => {
     it('has the right action type', () => {
diff --git a/packages/canvas-rce/test/sidebar/reducers/images.test.js b/packages/canvas-rce/test/sidebar/reducers/images.test.js
index 0c73d4bebae..1eb1b6bb502 100644
--- a/packages/canvas-rce/test/sidebar/reducers/images.test.js
+++ b/packages/canvas-rce/test/sidebar/reducers/images.test.js
@@ -17,6 +17,7 @@
  */
 
 import assert from 'assert'
+import {CHANGE_SEARCH_STRING} from '../../../src/sidebar/actions/filter'
 import images from '../../../src/sidebar/reducers/images'
 import * as actions from '../../../src/sidebar/actions/images'
 
@@ -31,7 +32,8 @@ describe('Images reducer', () => {
         hasMore: false,
         isLoading: false
       },
-      contextType: 'course'
+      contextType: 'course',
+      searchString: ''
     }
   })
 
@@ -93,17 +95,34 @@ describe('Images reducer', () => {
   })
 
   describe('RECEIVE_IMAGES', () => {
-    it('appends new records to the existing array', () => {
+    it('appends new records to the existing array when the payload searchString matches state', () => {
       const action = {
         type: actions.RECEIVE_IMAGES,
         payload: {
           files: [{id: 1}, {id: 2}],
-          contextType: 'course'
+          contextType: 'course',
+          searchString: 'panda'
         }
       }
+
+      state.searchString = 'panda'
       assert.equal(images(state, action).course.files.length, 2)
     })
 
+    it('does not append new records to the existing array when the payload searchString does not match state', () => {
+      const action = {
+        type: actions.RECEIVE_IMAGES,
+        payload: {
+          files: [{id: 1}, {id: 2}],
+          contextType: 'course',
+          searchString: 'panda'
+        }
+      }
+
+      state.searchString = 'cat'
+      assert.equal(images(state, action).course.files.length, 0)
+    })
+
     it("hasMore if there's a bookmark", () => {
       const action = {
         type: actions.RECEIVE_IMAGES,
@@ -153,4 +172,11 @@ describe('Images reducer', () => {
       assert.equal(images(state, action).course.files.length, 0)
     })
   })
+
+  describe('CHANGE_SEARCH_STRING', () => {
+    it('sets the searchString to the payload', () => {
+      const action = {type: CHANGE_SEARCH_STRING, payload: 'panda'}
+      assert.strictEqual(images(state, action).searchString, 'panda')
+    })
+  })
 })
diff --git a/packages/canvas-rce/test/sidebar/sources/api.test.js b/packages/canvas-rce/test/sidebar/sources/api.test.js
index 03068fb9adb..2d0e727eb65 100644
--- a/packages/canvas-rce/test/sidebar/sources/api.test.js
+++ b/packages/canvas-rce/test/sidebar/sources/api.test.js
@@ -86,6 +86,10 @@ describe('sources/api', () => {
     it('sets hasMore to true', () => {
       assert.strictEqual(apiSource.initializeImages(props)[props.contextType].hasMore, true)
     })
+
+    it('sets searchString to an empty string', () => {
+      assert.strictEqual(apiSource.initializeImages(props).searchString, '')
+    })
   })
 
   describe('URI construction (baseUri)', () => {
@@ -731,6 +735,7 @@ describe('sources/api', () => {
         files: []
       }
     }
+    props.searchString = 'panda'
 
     it('can fetch folders', () => {
       fetchMock.mock(/\/folders\?/, {body})
@@ -745,7 +750,8 @@ describe('sources/api', () => {
       return apiSource.fetchImages(props).then(page => {
         assert.deepStrictEqual(page, {
           bookmark: 'mo.images',
-          files: [{href: '/some/where?wrap=1', uuid: 'xyzzy'}]
+          files: [{href: '/some/where?wrap=1', uuid: 'xyzzy'}],
+          searchString: 'panda'
         })
         fetchMock.restore()
       })