diff --git a/src/lib/components/AssistantSettings.svelte b/src/lib/components/AssistantSettings.svelte
index d99d8b52a27..db973397c0f 100644
--- a/src/lib/components/AssistantSettings.svelte
+++ b/src/lib/components/AssistantSettings.svelte
@@ -50,7 +50,14 @@
 
 	function onFilesChange(e: Event) {
 		const inputEl = e.target as HTMLInputElement;
-		if (inputEl.files?.length) {
+		if (inputEl.files?.length && inputEl.files[0].size > 0) {
+			if (!inputEl.files[0].type.includes("image")) {
+				inputEl.files = null;
+				files = null;
+
+				form = { error: true, errors: [{ field: "avatar", message: "Only images are allowed" }] };
+				return;
+			}
 			files = inputEl.files;
 			resetErrors();
 			deleteExistingAvatar = false;
@@ -90,6 +97,10 @@
 				// else we just remove it from the input
 				formData.delete("avatar");
 			}
+		} else {
+			if (files === null) {
+				formData.delete("avatar");
+			}
 		}
 
 		return async ({ result }) => {
@@ -135,7 +146,7 @@
 							/>
 						{:else if assistant?.avatar}
 							<img
-								src="{base}/settings/assistants/{assistant._id}/avatar?hash={assistant.avatar}"
+								src="{base}/settings/assistants/{assistant._id}/avatar.jpg?hash={assistant.avatar}"
 								alt="avatar"
 								class="crop mx-auto h-12 w-12 cursor-pointer rounded-full object-cover"
 							/>
@@ -169,8 +180,8 @@
 							<CarbonUpload class="mr-2 text-xs " /> Upload
 						</label>
 					</div>
-					<p class="text-xs text-red-500">{getError("avatar", form)}</p>
 				{/if}
+				<p class="text-xs text-red-500">{getError("avatar", form)}</p>
 			</div>
 
 			<label>
diff --git a/src/lib/components/NavConversationItem.svelte b/src/lib/components/NavConversationItem.svelte
index 3835491a944..9c0e7471479 100644
--- a/src/lib/components/NavConversationItem.svelte
+++ b/src/lib/components/NavConversationItem.svelte
@@ -36,7 +36,7 @@
 		{/if}
 		{#if conv.avatarHash}
 			<img
-				src="{base}/settings/assistants/{conv.assistantId}/avatar?hash={conv.avatarHash}"
+				src="{base}/settings/assistants/{conv.assistantId}/avatar.jpg?hash={conv.avatarHash}"
 				alt="Assistant avatar"
 				class="mr-1.5 inline size-4 flex-none rounded-full object-cover"
 			/>
diff --git a/src/lib/components/chat/AssistantIntroduction.svelte b/src/lib/components/chat/AssistantIntroduction.svelte
index daebdef961a..19f7c38f9e8 100644
--- a/src/lib/components/chat/AssistantIntroduction.svelte
+++ b/src/lib/components/chat/AssistantIntroduction.svelte
@@ -21,7 +21,7 @@
 		>
 			{#if assistant.avatar}
 				<img
-					src={`${base}/settings/assistants/${assistant._id.toString()}/avatar?hash=${
+					src={`${base}/settings/assistants/${assistant._id.toString()}/avatar.jpg?hash=${
 						assistant.avatar
 					}`}
 					alt="avatar"
diff --git a/src/lib/components/chat/ChatMessages.svelte b/src/lib/components/chat/ChatMessages.svelte
index f938fd441ec..2db4b6dd096 100644
--- a/src/lib/components/chat/ChatMessages.svelte
+++ b/src/lib/components/chat/ChatMessages.svelte
@@ -54,8 +54,8 @@
 				>
 					{#if $page.data?.assistant.avatar}
 						<img
-							src="{base}/settings/assistants/{$page.data?.assistant._id.toString()}/avatar?hash=${$page
-								.data?.assistant.avatar}"
+							src="{base}/settings/assistants/{$page.data?.assistant._id.toString()}/avatar.jpg?hash=${$page
+								.data.assistant.avatar}"
 							alt="Avatar"
 							class="size-5 rounded-full object-cover"
 						/>
diff --git a/src/routes/assistant/[assistantId]/+page.svelte b/src/routes/assistant/[assistantId]/+page.svelte
index 6ac9fc8fa37..b60780d0ac6 100644
--- a/src/routes/assistant/[assistantId]/+page.svelte
+++ b/src/routes/assistant/[assistantId]/+page.svelte
@@ -50,7 +50,8 @@
 		{#if data.assistant.avatar}
 			<img
 				class="size-16 flex-none rounded-full object-cover sm:size-24"
-				src="{base}/settings/assistants/{data.assistant._id}/avatar?hash={data.assistant.avatar}"
+				src="{base}/settings/assistants/{data.assistant._id}/avatar.jpg?hash={data.assistant
+					.avatar}"
 				alt="avatar"
 			/>
 		{:else}
diff --git a/src/routes/assistants/+page.svelte b/src/routes/assistants/+page.svelte
index 0611e2c8117..dbe36c31f96 100644
--- a/src/routes/assistants/+page.svelte
+++ b/src/routes/assistants/+page.svelte
@@ -79,7 +79,7 @@
 				>
 					{#if assistant.avatar}
 						<img
-							src="{base}/settings/assistants/{assistant._id}/avatar"
+							src="{base}/settings/assistants/{assistant._id}/avatar.jpg"
 							alt="Avatar"
 							class="mb-2 aspect-square size-12 flex-none rounded-full object-cover sm:mb-6 sm:size-20"
 						/>
diff --git a/src/routes/settings/+layout.svelte b/src/routes/settings/+layout.svelte
index ce235736e75..a90506e64cd 100644
--- a/src/routes/settings/+layout.svelte
+++ b/src/routes/settings/+layout.svelte
@@ -101,7 +101,7 @@
 					>
 						{#if assistant.avatar}
 							<img
-								src="{base}/settings/assistants/{assistant._id.toString()}/avatar?hash={assistant.avatar}"
+								src="{base}/settings/assistants/{assistant._id.toString()}/avatar.jpg?hash={assistant.avatar}"
 								alt="Avatar"
 								class="h-6 w-6 rounded-full object-cover"
 							/>
diff --git a/src/routes/settings/assistants/[assistantId]/+page.svelte b/src/routes/settings/assistants/[assistantId]/+page.svelte
index 976201fc0de..f2ed1a87ff0 100644
--- a/src/routes/settings/assistants/[assistantId]/+page.svelte
+++ b/src/routes/settings/assistants/[assistantId]/+page.svelte
@@ -31,7 +31,7 @@
 		{#if assistant?.avatar}
 			<!-- crop image if not square  -->
 			<img
-				src={`${base}/settings/assistants/${assistant?._id}/avatar?hash=${assistant?.avatar}`}
+				src={`${base}/settings/assistants/${assistant?._id}/avatar.jpg?hash=${assistant?.avatar}`}
 				alt="Avatar"
 				class="size-16 flex-none rounded-full object-cover sm:size-24"
 			/>
diff --git a/src/routes/settings/assistants/[assistantId]/avatar/+server.ts b/src/routes/settings/assistants/[assistantId]/avatar.jpg/+server.ts
similarity index 91%
rename from src/routes/settings/assistants/[assistantId]/avatar/+server.ts
rename to src/routes/settings/assistants/[assistantId]/avatar.jpg/+server.ts
index 0b6be2c2cf6..23f2025610a 100644
--- a/src/routes/settings/assistants/[assistantId]/avatar/+server.ts
+++ b/src/routes/settings/assistants/[assistantId]/avatar.jpg/+server.ts
@@ -17,11 +17,7 @@ export const GET: RequestHandler = async ({ params }) => {
 
 	const fileId = collections.bucket.find({ filename: assistant._id.toString() });
 
-	let mime = "";
-
 	const content = await fileId.next().then(async (file) => {
-		mime = file?.metadata?.mime;
-
 		if (!file?._id) {
 			throw error(404, "Avatar not found");
 		}
@@ -40,7 +36,7 @@ export const GET: RequestHandler = async ({ params }) => {
 
 	return new Response(content, {
 		headers: {
-			"Content-Type": mime ?? "application/octet-stream",
+			"Content-Type": "image/jpeg",
 		},
 	});
 };
diff --git a/src/routes/settings/assistants/[assistantId]/edit/+page.server.ts b/src/routes/settings/assistants/[assistantId]/edit/+page.server.ts
index 66306232cdc..9310324ab6d 100644
--- a/src/routes/settings/assistants/[assistantId]/edit/+page.server.ts
+++ b/src/routes/settings/assistants/[assistantId]/edit/+page.server.ts
@@ -5,9 +5,10 @@ import { fail, type Actions, redirect } from "@sveltejs/kit";
 import { ObjectId } from "mongodb";
 
 import { z } from "zod";
-import sizeof from "image-size";
 import { sha256 } from "$lib/utils/sha256";
 
+import sharp from "sharp";
+
 const newAsssistantSchema = z.object({
 	name: z.string().min(1),
 	modelId: z.string().min(1),
@@ -84,10 +85,14 @@ export const actions: Actions = {
 
 		let hash;
 		if (parse.data.avatar && parse.data.avatar !== "null" && parse.data.avatar.size > 0) {
-			const dims = sizeof(Buffer.from(await parse.data.avatar.arrayBuffer()));
-
-			if ((dims.height ?? 1000) > 512 || (dims.width ?? 1000) > 512) {
-				const errors = [{ field: "avatar", message: "Avatar too big" }];
+			let image;
+			try {
+				image = await sharp(await parse.data.avatar.arrayBuffer())
+					.resize(512, 512, { fit: "inside" })
+					.jpeg({ quality: 80 })
+					.toBuffer();
+			} catch (e) {
+				const errors = [{ field: "avatar", message: (e as Error).message }];
 				return fail(400, { error: true, errors });
 			}
 
@@ -100,7 +105,7 @@ export const actions: Actions = {
 				fileId = await fileCursor.next();
 			}
 
-			hash = await uploadAvatar(parse.data.avatar, assistant._id);
+			hash = await uploadAvatar(new File([image], "avatar.jpg"), assistant._id);
 		} else if (deleteAvatar) {
 			// delete the avatar
 			const fileCursor = collections.bucket.find({ filename: assistant._id.toString() });
diff --git a/src/routes/settings/assistants/new/+page.server.ts b/src/routes/settings/assistants/new/+page.server.ts
index cafae987d3b..f58adabd91f 100644
--- a/src/routes/settings/assistants/new/+page.server.ts
+++ b/src/routes/settings/assistants/new/+page.server.ts
@@ -5,8 +5,8 @@ import { fail, type Actions, redirect } from "@sveltejs/kit";
 import { ObjectId } from "mongodb";
 
 import { z } from "zod";
-import sizeof from "image-size";
 import { sha256 } from "$lib/utils/sha256";
+import sharp from "sharp";
 
 const newAsssistantSchema = z.object({
 	name: z.string().min(1),
@@ -74,20 +74,18 @@ export const actions: Actions = {
 
 		let hash;
 		if (parse.data.avatar && parse.data.avatar.size > 0) {
-			const dims = sizeof(Buffer.from(await parse.data.avatar.arrayBuffer()));
-
-			if ((dims.height ?? 1000) > 512 || (dims.width ?? 1000) > 512) {
-				const errors = [
-					{
-						field: "avatar",
-						message:
-							"Avatar is too big. Please make sure the size of your avatar is no bigger than 512px by 512px.",
-					},
-				];
+			let image;
+			try {
+				image = await sharp(await parse.data.avatar.arrayBuffer())
+					.resize(512, 512, { fit: "inside" })
+					.jpeg({ quality: 80 })
+					.toBuffer();
+			} catch (e) {
+				const errors = [{ field: "avatar", message: (e as Error).message }];
 				return fail(400, { error: true, errors });
 			}
 
-			hash = await uploadAvatar(parse.data.avatar, newAssistantId);
+			hash = await uploadAvatar(new File([image], "avatar.jpg"), newAssistantId);
 		}
 
 		const { insertedId } = await collections.assistants.insertOne({