diff --git a/ui/serve.go b/ui/serve.go
index 1e054c81..b7d0d401 100644
--- a/ui/serve.go
+++ b/ui/serve.go
@@ -3,7 +3,6 @@ package ui
 import (
 	"fmt"
 	"io"
-	"mime"
 	"net/http"
 	"net/url"
 	"path/filepath"
@@ -143,7 +142,7 @@ func ServeFileFromBundle(w http.ResponseWriter, r *http.Request, bundleName stri
 	// set content type
 	_, ok := w.Header()["Content-Type"]
 	if !ok {
-		contentType := mime.TypeByExtension(filepath.Ext(path))
+		contentType := mimeTypeByExtension(filepath.Ext(path))
 		if contentType != "" {
 			w.Header().Set("Content-Type", contentType)
 		}
@@ -179,3 +178,72 @@ func redirectToDefault(w http.ResponseWriter, r *http.Request) {
 func redirAddSlash(w http.ResponseWriter, r *http.Request) {
 	http.Redirect(w, r, r.RequestURI+"/", http.StatusPermanentRedirect)
 }
+
+// We now do our mimetypes ourselves, because, as far as we analyzed, a Windows
+// update screwed us over here and broke all the mime typing.
+// (April 2021)
+
+var (
+	defaultMimeType = "application/octet-stream"
+
+	mimeTypes = map[string]string{
+		".7z":    "application/x-7z-compressed",
+		".atom":  "application/atom+xml",
+		".css":   "text/css; charset=utf-8",
+		".csv":   "text/csv; charset=utf-8",
+		".deb":   "application/x-debian-package",
+		".epub":  "application/epub+zip",
+		".es":    "application/ecmascript",
+		".flv":   "video/x-flv",
+		".gif":   "image/gif",
+		".gz":    "application/gzip",
+		".htm":   "text/html; charset=utf-8",
+		".html":  "text/html; charset=utf-8",
+		".jpeg":  "image/jpeg",
+		".jpg":   "image/jpeg",
+		".js":    "text/javascript; charset=utf-8",
+		".json":  "application/json",
+		".m3u":   "audio/mpegurl",
+		".m4a":   "audio/mpeg",
+		".md":    "text/markdown; charset=utf-8",
+		".mjs":   "text/javascript; charset=utf-8",
+		".mov":   "video/quicktime",
+		".mp3":   "audio/mpeg",
+		".mp4":   "video/mp4",
+		".mpeg":  "video/mpeg",
+		".mpg":   "video/mpeg",
+		".ogg":   "audio/ogg",
+		".ogv":   "video/ogg",
+		".otf":   "font/otf",
+		".pdf":   "application/pdf",
+		".png":   "image/png",
+		".qt":    "video/quicktime",
+		".rar":   "application/rar",
+		".rtf":   "application/rtf",
+		".svg":   "image/svg+xml",
+		".tar":   "application/x-tar",
+		".tiff":  "image/tiff",
+		".ts":    "video/MP2T",
+		".ttc":   "font/collection",
+		".ttf":   "font/ttf",
+		".txt":   "text/plain; charset=utf-8",
+		".wasm":  "application/wasm",
+		".wav":   "audio/x-wav",
+		".webm":  "video/webm",
+		".webp":  "image/webp",
+		".woff":  "font/woff",
+		".woff2": "font/woff2",
+		".xml":   "text/xml; charset=utf-8",
+		".xz":    "application/x-xz",
+		".zip":   "application/zip",
+	}
+)
+
+func mimeTypeByExtension(ext string) string {
+	mimeType, ok := mimeTypes[ext]
+	if ok {
+		return mimeType
+	}
+
+	return defaultMimeType
+}