diff --git a/packages/lib-classifier/src/components/Classifier/components/SubjectViewer/components/MultiFrameViewer/MultiFrameViewerContainer.js b/packages/lib-classifier/src/components/Classifier/components/SubjectViewer/components/MultiFrameViewer/MultiFrameViewerContainer.js
index 0e3d41552c..597611f28d 100644
--- a/packages/lib-classifier/src/components/Classifier/components/SubjectViewer/components/MultiFrameViewer/MultiFrameViewerContainer.js
+++ b/packages/lib-classifier/src/components/Classifier/components/SubjectViewer/components/MultiFrameViewer/MultiFrameViewerContainer.js
@@ -13,7 +13,6 @@ import locationValidator from '../../helpers/locationValidator'
 import SingleImageViewer from '../SingleImageViewer/SingleImageViewer'
 import SVGPanZoom from '../SVGComponents/SVGPanZoom'
 
-
 function storeMapper(store) {
   const {
     enableRotation,
@@ -25,7 +24,17 @@ function storeMapper(store) {
     setOnZoom
   } = store.subjectViewer
 
+  const { activeStepTasks } = store.workflowSteps
+
+  const [activeInteractionTask] = activeStepTasks.filter(
+    (task) => task.type === 'drawing' || task.type === 'transcription'
+  )
+  const {
+    activeTool
+  } = activeInteractionTask || {}
+
   return {
+    activeTool,
     enableRotation,
     frame,
     move,
@@ -48,7 +57,7 @@ class MultiFrameViewerContainer extends React.Component {
     this.setOnDrag = this.setOnDrag.bind(this)
 
     this.subjectImage = React.createRef()
-    
+
     this.state = {
       img: {}
     }
@@ -86,7 +95,15 @@ class MultiFrameViewerContainer extends React.Component {
   }
 
   onFrameChange(frame) {
-    const { setFrame } = this.props
+    const {
+      activeTool,
+      setFrame
+    } = this.props
+
+    if (activeTool?.marks?.size > 0) {
+      activeTool.validate()
+    }
+
     setFrame(frame)
   }
 
@@ -139,7 +156,7 @@ class MultiFrameViewerContainer extends React.Component {
       subject
     } = this.props
     const { img } = this.state
-    
+
     // If image hasn't been fully retrieved, use a placeholder
     const src = img?.src || 'https://static.zooniverse.org/www.zooniverse.org/assets/fe-project-subject-placeholder-800x600.png'  // Use this instead of https://www.zooniverse.org/assets/fe-project-subject-placeholder-800x600.png to save on network calls
     const naturalWidth = img?.naturalWidth || 800
@@ -204,6 +221,9 @@ class MultiFrameViewerContainer extends React.Component {
 }
 
 MultiFrameViewerContainer.propTypes = {
+  activeTool: PropTypes.shape({
+    validate: PropTypes.func
+  }),
   enableInteractionLayer: PropTypes.bool,
   enableRotation: PropTypes.func,
   frame: PropTypes.number,
@@ -219,6 +239,9 @@ MultiFrameViewerContainer.propTypes = {
 }
 
 MultiFrameViewerContainer.defaultProps = {
+  activeTool: {
+    validate: () => {}
+  },
   enableInteractionLayer: true,
   enableRotation: () => null,
   frame: 0,
diff --git a/packages/lib-classifier/src/components/Classifier/components/SubjectViewer/components/MultiFrameViewer/MultiFrameViewerContainer.spec.js b/packages/lib-classifier/src/components/Classifier/components/SubjectViewer/components/MultiFrameViewer/MultiFrameViewerContainer.spec.js
index 5b55177ac7..4c29119e24 100644
--- a/packages/lib-classifier/src/components/Classifier/components/SubjectViewer/components/MultiFrameViewer/MultiFrameViewerContainer.spec.js
+++ b/packages/lib-classifier/src/components/Classifier/components/SubjectViewer/components/MultiFrameViewer/MultiFrameViewerContainer.spec.js
@@ -5,6 +5,7 @@ import React from 'react'
 import { DraggableImage, MultiFrameViewerContainer } from './MultiFrameViewerContainer'
 import FrameCarousel from './FrameCarousel'
 import SingleImageViewer from '../SingleImageViewer/SingleImageViewer'
+import TranscriptionLineTool from '../../../../../../plugins/drawingTools/experimental/models/tools/TranscriptionLineTool/TranscriptionLineTool'
 import asyncStates from '@zooniverse/async-states'
 
 describe('Component > MultiFrameViewerContainer', function () {
@@ -140,7 +141,31 @@ describe('Component > MultiFrameViewerContainer', function () {
         expect(image).to.have.lengthOf(1)
         expect(image.prop('xlinkHref')).to.equal('https://some.domain/image.jpg')
       })
-    })  
+    })
+
+    describe('with invalid marks', function () {
+      // mock an active transcription task tool:
+      const activeTool = TranscriptionLineTool.create({
+        color: '#ff0000',
+        type: 'transcriptionLine'
+      })
+
+      // add a valid first mark:
+      const pointerEvent = { x: 10, y: 10 }
+      const validMark = activeTool.createMark({ x: 0, y: 0 })
+      activeTool.handlePointerDown(pointerEvent, validMark)
+
+      // add an invalid second mark (start, but don't finish a line):
+      activeTool.createMark({ x: 15, y: 15 })
+
+      it('should delete invalid marks on frame change', function () {
+        wrapper.setProps({ activeTool })
+        expect(activeTool.marks.size).to.equal(2)
+
+        wrapper.instance().onFrameChange(2)
+        expect(activeTool.marks.size).to.equal(1)
+      })
+    })
   })
 
   describe('with an invalid subject', function () {