diff --git a/src/components/Roms/RomsInteractive.tsx b/src/components/Roms/RomsInteractive.tsx
index e32b675..0d74d93 100644
--- a/src/components/Roms/RomsInteractive.tsx
+++ b/src/components/Roms/RomsInteractive.tsx
@@ -5,6 +5,9 @@ import { FaTriangleExclamation } from "react-icons/fa6";
 import { baseRoms } from "@/data/baseRoms";
 import { useBaseRoms } from "@/contexts/BaseRomContext";
 import BaseRomCard from "@/components/BaseRomCard";
+import { platformAcceptAll } from "@/utils/idb";
+
+const ALLOWED_TYPES = platformAcceptAll().split(",");
 
 export default function RomsInteractive() {
   const { supported, linked, statuses, cached, totalCachedBytes, importUploadedBlob, importToCache, removeFromCache, unlinkRom, ensurePermission, countReady } = useBaseRoms();
@@ -59,6 +62,10 @@ export default function RomsInteractive() {
             setDragActive(false);
             const file = e.dataTransfer?.files?.[0];
             if (!file) return;
+            if (!ALLOWED_TYPES.includes(`.${file.name.split(".").pop()?.toLowerCase() ?? ""}`)) {
+              setUploadMsg(`Unrecognized file. Not cached. Accepted types: ${ALLOWED_TYPES.join(", ")}`);
+              return;
+            }
             const name = await importUploadedBlob(file);
             if (name) setUploadMsg(`Recognized and cached: ${name}`);
             else setUploadMsg("Unrecognized ROM. Not cached.");
@@ -76,7 +83,7 @@ export default function RomsInteractive() {
               </div>
             </div>
             <label className="inline-flex cursor-pointer items-center justify-center rounded-md bg-[var(--accent)] px-3 py-2 text-sm font-medium text-[var(--accent-foreground)] transition-colors hover:bg-[var(--accent-700)]">
-              <input type="file" onChange={onUpload} className="hidden" />
+              <input type="file" onChange={onUpload} className="hidden" accept={platformAcceptAll()} />
               Choose file…
             </label>
           </div>
diff --git a/src/data/baseRoms.ts b/src/data/baseRoms.ts
index 1a9a94f..c2a4f18 100644
--- a/src/data/baseRoms.ts
+++ b/src/data/baseRoms.ts
@@ -1,7 +1,15 @@
+export const PLATFORMS = [
+  "GB",
+  "GBC",
+  "GBA",
+  "NDS",
+] as const;
+export type Platform = typeof PLATFORMS[number];
+
 export type BaseRom = {
   id: string;
   name: string;
-  platform: "GB" | "GBC" | "GBA" | "NDS";
+  platform: Platform;
   region: string;
   sha1?: string;
 };
diff --git a/src/utils/idb.ts b/src/utils/idb.ts
index 34cbe09..0fb2b8d 100644
--- a/src/utils/idb.ts
+++ b/src/utils/idb.ts
@@ -1,4 +1,6 @@
 // Minimal IndexedDB helpers for storing FileSystemFileHandle references
+import type { Platform } from "@/data/baseRoms";
+import { PLATFORMS } from "@/data/baseRoms";
 
 const DB_NAME = "romhaven";
 const DB_VERSION = 2;
@@ -113,4 +115,31 @@ export async function getAllBlobEntries(): Promise<Array<{ name: string; blob: B
   });
 }
 
+export function platformAccept(p: Platform | Platform[]): string {
+  if (Array.isArray(p)) {
+    // Gather all individual extensions and dedupe
+    const extSet = new Set<string>();
+    for (const plat of p) {
+      const exts = platformAccept(plat).split(",");
+      for (const ext of exts) {
+        extSet.add(ext.trim());
+      }
+    }
+    return Array.from(extSet).join(",");
+  }
 
+  // Exhaustive check using a mapping object for platform strings
+  const mapping: Record<Platform, string> = {
+    GB: ".gb",
+    GBC: ".gbc,.gb",
+    GBA: ".gba",
+    NDS: ".nds",
+  };
+
+  // If `p` is not a valid Platform, TypeScript will error here.
+  return mapping[p];
+}
+
+export function platformAcceptAll(): string {
+  return platformAccept([...PLATFORMS]);
+}