diff --git a/invokeai/frontend/web/src/common/hooks/useImageUploadButton.tsx b/invokeai/frontend/web/src/common/hooks/useImageUploadButton.tsx
index ff53b8ec79..9a06dab639 100644
--- a/invokeai/frontend/web/src/common/hooks/useImageUploadButton.tsx
+++ b/invokeai/frontend/web/src/common/hooks/useImageUploadButton.tsx
@@ -6,7 +6,7 @@ import { selectAutoAddBoardId } from 'features/gallery/store/gallerySelectors';
 import { selectIsClientSideUploadEnabled } from 'features/system/store/configSlice';
 import { toast } from 'features/toast/toast';
 import { memo, useCallback } from 'react';
-import type { FileRejection } from 'react-dropzone';
+import type { Accept, FileRejection } from 'react-dropzone';
 import { useDropzone } from 'react-dropzone';
 import { useTranslation } from 'react-i18next';
 import { PiUploadBold } from 'react-icons/pi';
@@ -15,6 +15,18 @@ import type { ImageDTO } from 'services/api/types';
 import { assert } from 'tsafe';
 import type { SetOptional } from 'type-fest';
 
+const addUpperCaseReducer = (acc: string[], ext: string) => {
+  acc.push(ext);
+  acc.push(ext.toUpperCase());
+  return acc;
+};
+
+export const dropzoneAccept: Accept = {
+  'image/png': ['.png'].reduce(addUpperCaseReducer, [] as string[]),
+  'image/jpeg': ['.jpg', '.jpeg', '.png'].reduce(addUpperCaseReducer, [] as string[]),
+  'image/webp': ['.webp'].reduce(addUpperCaseReducer, [] as string[]),
+};
+
 import { useClientSideUpload } from './useClientSideUpload';
 type UseImageUploadButtonArgs =
   | {
@@ -164,11 +176,7 @@ export const useImageUploadButton = ({
     getInputProps: getUploadInputProps,
     open: openUploader,
   } = useDropzone({
-    accept: {
-      'image/png': ['.png'],
-      'image/jpeg': ['.jpg', '.jpeg', '.png'],
-      'image/webp': ['.webp'],
-    },
+    accept: dropzoneAccept,
     onDropAccepted,
     onDropRejected,
     disabled: isDisabled,
diff --git a/invokeai/frontend/web/src/features/dnd/FullscreenDropzone.tsx b/invokeai/frontend/web/src/features/dnd/FullscreenDropzone.tsx
index 0481a32251..bb890ed7eb 100644
--- a/invokeai/frontend/web/src/features/dnd/FullscreenDropzone.tsx
+++ b/invokeai/frontend/web/src/features/dnd/FullscreenDropzone.tsx
@@ -41,13 +41,13 @@ const zUploadFile = z
   // )
   .refine(
     (file) => {
-      return ACCEPTED_IMAGE_TYPES.includes(file.type);
+      return ACCEPTED_IMAGE_TYPES.includes(file.type.toLowerCase());
     },
     { message: `File type is not supported` }
   )
   .refine(
     (file) => {
-      return ACCEPTED_FILE_EXTENSIONS.some((ext) => file.name.endsWith(ext));
+      return ACCEPTED_FILE_EXTENSIONS.some((ext) => file.name.toLowerCase().endsWith(ext));
     },
     { message: `File extension is not supported` }
   );
diff --git a/invokeai/frontend/web/src/features/modelManagerV2/subpanels/ModelPanel/Fields/ModelImageUpload.tsx b/invokeai/frontend/web/src/features/modelManagerV2/subpanels/ModelPanel/Fields/ModelImageUpload.tsx
index d6ec53e33d..cde9955236 100644
--- a/invokeai/frontend/web/src/features/modelManagerV2/subpanels/ModelPanel/Fields/ModelImageUpload.tsx
+++ b/invokeai/frontend/web/src/features/modelManagerV2/subpanels/ModelPanel/Fields/ModelImageUpload.tsx
@@ -1,4 +1,5 @@
 import { Box, IconButton, Image } from '@invoke-ai/ui-library';
+import { dropzoneAccept } from 'common/hooks/useImageUploadButton';
 import { typedMemo } from 'common/util/typedMemo';
 import { toast } from 'features/toast/toast';
 import { useCallback, useState } from 'react';
@@ -72,11 +73,7 @@ const ModelImageUpload = ({ model_key, model_image }: Props) => {
   }, [model_key, t, deleteModelImage]);
 
   const { getInputProps, getRootProps } = useDropzone({
-    accept: {
-      'image/png': ['.png'],
-      'image/jpeg': ['.jpg', '.jpeg', '.png'],
-      'image/webp': ['.webp'],
-    },
+    accept: dropzoneAccept,
     onDropAccepted,
     noDrag: true,
     multiple: false,
diff --git a/invokeai/frontend/web/src/features/nodes/components/sidePanel/workflow/WorkflowThumbnail/WorkflowThumbnailField.tsx b/invokeai/frontend/web/src/features/nodes/components/sidePanel/workflow/WorkflowThumbnail/WorkflowThumbnailField.tsx
index 3438084904..6416baf41f 100644
--- a/invokeai/frontend/web/src/features/nodes/components/sidePanel/workflow/WorkflowThumbnail/WorkflowThumbnailField.tsx
+++ b/invokeai/frontend/web/src/features/nodes/components/sidePanel/workflow/WorkflowThumbnail/WorkflowThumbnailField.tsx
@@ -1,4 +1,5 @@
 import { Box, Button, Flex, Icon, IconButton, Image, Tooltip } from '@invoke-ai/ui-library';
+import { dropzoneAccept } from 'common/hooks/useImageUploadButton';
 import { convertImageUrlToBlob } from 'common/util/convertImageUrlToBlob';
 import { useCallback, useEffect, useState } from 'react';
 import { useDropzone } from 'react-dropzone';
@@ -53,7 +54,7 @@ export const WorkflowThumbnailField = ({
   }, [onChange]);
 
   const { getInputProps, getRootProps } = useDropzone({
-    accept: { 'image/png': ['.png'], 'image/jpeg': ['.jpg', '.jpeg', '.png'] },
+    accept: dropzoneAccept,
     onDropAccepted,
     noDrag: true,
     multiple: false,
diff --git a/invokeai/frontend/web/src/features/stylePresets/components/StylePresetForm/StylePresetImageField.tsx b/invokeai/frontend/web/src/features/stylePresets/components/StylePresetForm/StylePresetImageField.tsx
index 38eaac471a..089293d4e7 100644
--- a/invokeai/frontend/web/src/features/stylePresets/components/StylePresetForm/StylePresetImageField.tsx
+++ b/invokeai/frontend/web/src/features/stylePresets/components/StylePresetForm/StylePresetImageField.tsx
@@ -1,4 +1,5 @@
 import { Box, Button, Flex, Icon, IconButton, Image, Tooltip } from '@invoke-ai/ui-library';
+import { dropzoneAccept } from 'common/hooks/useImageUploadButton';
 import { useCallback } from 'react';
 import { useDropzone } from 'react-dropzone';
 import type { UseControllerProps } from 'react-hook-form';
@@ -26,7 +27,7 @@ export const StylePresetImageField = (props: UseControllerProps<StylePresetFormD
   }, [field]);
 
   const { getInputProps, getRootProps } = useDropzone({
-    accept: { 'image/png': ['.png'], 'image/jpeg': ['.jpg', '.jpeg', '.png'] },
+    accept: dropzoneAccept,
     onDropAccepted,
     noDrag: true,
     multiple: false,