diff --git a/public/scripts/network.js b/public/scripts/network.js
index 3d6e01b..6b7bb11 100644
--- a/public/scripts/network.js
+++ b/public/scripts/network.js
@@ -1082,20 +1082,9 @@ class PeersManager {
         this.peers[detail.to]._respondToFileTransferRequest(detail.accepted);
     }
 
-    _onFilesSelected(message) {
-        let inputFiles = Array.from(message.files);
-        delete message.files;
-        let files = [];
-        const l = inputFiles.length;
-        for (let i=0; i<l; i++) {
-            // when filetype is empty guess via suffix
-            const inputFile = inputFiles.shift();
-            const file = inputFile.type
-                ? inputFile
-                : new File([inputFile], inputFile.name, {type: mime.getMimeByFilename(inputFile.name)});
-            files.push(file)
-        }
-        this.peers[message.to].requestFileTransfer(files);
+    async _onFilesSelected(message) {
+        let files = await mime.addMissingMimeTypesToFiles(message.files);
+        await this.peers[message.to].requestFileTransfer(files);
     }
 
     _onSendText(message) {
diff --git a/public/scripts/ui.js b/public/scripts/ui.js
index d650fe0..6ff3a4c 100644
--- a/public/scripts/ui.js
+++ b/public/scripts/ui.js
@@ -272,6 +272,8 @@ class PeersUI {
                 descriptorInstructions = Localization.getTranslation("instructions.activate-share-mode-shared-file");
             }
 
+            files = await mime.addMissingMimeTypesToFiles(files);
+
             if (files[0].type.split('/')[0] === 'image') {
                 getResizedImageDataUrl(files[0], 80, null, 0.9)
                     .then(dataUrl => {
diff --git a/public/scripts/util.js b/public/scripts/util.js
index 3ef5488..ad86924 100644
--- a/public/scripts/util.js
+++ b/public/scripts/util.js
@@ -104,305 +104,315 @@ const zipper = (() => {
 
 const mime = (() => {
 
+    const suffixToMimeMap = {
+        "cpl": "application/cpl+xml",
+        "gpx": "application/gpx+xml",
+        "gz": "application/gzip",
+        "jar": "application/java-archive",
+        "war": "application/java-archive",
+        "ear": "application/java-archive",
+        "class": "application/java-vm",
+        "js": "application/javascript",
+        "mjs": "application/javascript",
+        "json": "application/json",
+        "map": "application/json",
+        "webmanifest": "application/manifest+json",
+        "doc": "application/msword",
+        "dot": "application/msword",
+        "wiz": "application/msword",
+        "bin": "application/octet-stream",
+        "dms": "application/octet-stream",
+        "lrf": "application/octet-stream",
+        "mar": "application/octet-stream",
+        "so": "application/octet-stream",
+        "dist": "application/octet-stream",
+        "distz": "application/octet-stream",
+        "pkg": "application/octet-stream",
+        "bpk": "application/octet-stream",
+        "dump": "application/octet-stream",
+        "elc": "application/octet-stream",
+        "deploy": "application/octet-stream",
+        "img": "application/octet-stream",
+        "msp": "application/octet-stream",
+        "msm": "application/octet-stream",
+        "buffer": "application/octet-stream",
+        "oda": "application/oda",
+        "oxps": "application/oxps",
+        "pdf": "application/pdf",
+        "asc": "application/pgp-signature",
+        "sig": "application/pgp-signature",
+        "prf": "application/pics-rules",
+        "p7c": "application/pkcs7-mime",
+        "cer": "application/pkix-cert",
+        "ai": "application/postscript",
+        "eps": "application/postscript",
+        "ps": "application/postscript",
+        "apk": "application/vnd.android.package-archive",
+        "m3u8": "application/vnd.apple.mpegurl",
+        "pkpass": "application/vnd.apple.pkpass",
+        "kml": "application/vnd.google-earth.kml+xml",
+        "kmz": "application/vnd.google-earth.kmz",
+        "cab": "application/vnd.ms-cab-compressed",
+        "xls": "application/vnd.ms-excel",
+        "xlm": "application/vnd.ms-excel",
+        "xla": "application/vnd.ms-excel",
+        "xlc": "application/vnd.ms-excel",
+        "xlt": "application/vnd.ms-excel",
+        "xlw": "application/vnd.ms-excel",
+        "msg": "application/vnd.ms-outlook",
+        "ppt": "application/vnd.ms-powerpoint",
+        "pot": "application/vnd.ms-powerpoint",
+        "ppa": "application/vnd.ms-powerpoint",
+        "pps": "application/vnd.ms-powerpoint",
+        "pwz": "application/vnd.ms-powerpoint",
+        "mpp": "application/vnd.ms-project",
+        "mpt": "application/vnd.ms-project",
+        "xps": "application/vnd.ms-xpsdocument",
+        "odb": "application/vnd.oasis.opendocument.database",
+        "ods": "application/vnd.oasis.opendocument.spreadsheet",
+        "odt": "application/vnd.oasis.opendocument.text",
+        "osm": "application/vnd.openstreetmap.data+xml",
+        "pptx": "application/vnd.openxmlformats-officedocument.presentationml.presentation",
+        "xlsx": "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
+        "docx": "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
+        "pcap": "application/vnd.tcpdump.pcap",
+        "cap": "application/vnd.tcpdump.pcap",
+        "dmp": "application/vnd.tcpdump.pcap",
+        "wpd": "application/vnd.wordperfect",
+        "wasm": "application/wasm",
+        "7z": "application/x-7z-compressed",
+        "dmg": "application/x-apple-diskimage",
+        "bcpio": "application/x-bcpio",
+        "torrent": "application/x-bittorrent",
+        "cbr": "application/x-cbr",
+        "cba": "application/x-cbr",
+        "cbt": "application/x-cbr",
+        "cbz": "application/x-cbr",
+        "cb7": "application/x-cbr",
+        "vcd": "application/x-cdlink",
+        "crx": "application/x-chrome-extension",
+        "cpio": "application/x-cpio",
+        "csh": "application/x-csh",
+        "deb": "application/x-debian-package",
+        "udeb": "application/x-debian-package",
+        "dvi": "application/x-dvi",
+        "arc": "application/x-freearc",
+        "gtar": "application/x-gtar",
+        "hdf": "application/x-hdf",
+        "h5": "application/x-hdf5",
+        "php": "application/x-httpd-php",
+        "iso": "application/x-iso9660-image",
+        "key": "application/x-iwork-keynote-sffkey",
+        "numbers": "application/x-iwork-numbers-sffnumbers",
+        "pages": "application/x-iwork-pages-sffpages",
+        "latex": "application/x-latex",
+        "run": "application/x-makeself",
+        "mif": "application/x-mif",
+        "lnk": "application/x-ms-shortcut",
+        "mdb": "application/x-msaccess",
+        "exe": "application/x-msdownload",
+        "dll": "application/x-msdownload",
+        "com": "application/x-msdownload",
+        "bat": "application/x-msdownload",
+        "msi": "application/x-msdownload",
+        "pub": "application/x-mspublisher",
+        "cdf": "application/x-netcdf",
+        "nc": "application/x-netcdf",
+        "pl": "application/x-perl",
+        "pm": "application/x-perl",
+        "prc": "application/x-pilot",
+        "pdb": "application/x-pilot",
+        "p12": "application/x-pkcs12",
+        "pfx": "application/x-pkcs12",
+        "ram": "application/x-pn-realaudio",
+        "pyc": "application/x-python-code",
+        "pyo": "application/x-python-code",
+        "rar": "application/x-rar-compressed",
+        "rpm": "application/x-redhat-package-manager",
+        "sh": "application/x-sh",
+        "shar": "application/x-shar",
+        "swf": "application/x-shockwave-flash",
+        "sql": "application/x-sql",
+        "srt": "application/x-subrip",
+        "sv4cpio": "application/x-sv4cpio",
+        "sv4crc": "application/x-sv4crc",
+        "gam": "application/x-tads",
+        "tar": "application/x-tar",
+        "tcl": "application/x-tcl",
+        "tex": "application/x-tex",
+        "roff": "application/x-troff",
+        "t": "application/x-troff",
+        "tr": "application/x-troff",
+        "man": "application/x-troff-man",
+        "me": "application/x-troff-me",
+        "ms": "application/x-troff-ms",
+        "ustar": "application/x-ustar",
+        "src": "application/x-wais-source",
+        "xpi": "application/x-xpinstall",
+        "xhtml": "application/xhtml+xml",
+        "xht": "application/xhtml+xml",
+        "xsl": "application/xml",
+        "rdf": "application/xml",
+        "wsdl": "application/xml",
+        "xpdl": "application/xml",
+        "zip": "application/zip",
+        "3gp": "audio/3gp",
+        "3gpp": "audio/3gpp",
+        "3g2": "audio/3gpp2",
+        "3gpp2": "audio/3gpp2",
+        "aac": "audio/aac",
+        "adts": "audio/aac",
+        "loas": "audio/aac",
+        "ass": "audio/aac",
+        "au": "audio/basic",
+        "snd": "audio/basic",
+        "mid": "audio/midi",
+        "midi": "audio/midi",
+        "kar": "audio/midi",
+        "rmi": "audio/midi",
+        "mpga": "audio/mpeg",
+        "mp2": "audio/mpeg",
+        "mp2a": "audio/mpeg",
+        "mp3": "audio/mpeg",
+        "m2a": "audio/mpeg",
+        "m3a": "audio/mpeg",
+        "oga": "audio/ogg",
+        "ogg": "audio/ogg",
+        "spx": "audio/ogg",
+        "opus": "audio/opus",
+        "aif": "audio/x-aiff",
+        "aifc": "audio/x-aiff",
+        "aiff": "audio/x-aiff",
+        "flac": "audio/x-flac",
+        "m4a": "audio/x-m4a",
+        "m3u": "audio/x-mpegurl",
+        "wma": "audio/x-ms-wma",
+        "ra": "audio/x-pn-realaudio",
+        "wav": "audio/x-wav",
+        "otf": "font/otf",
+        "ttf": "font/ttf",
+        "woff": "font/woff",
+        "woff2": "font/woff2",
+        "emf": "image/emf",
+        "gif": "image/gif",
+        "heic": "image/heic",
+        "heif": "image/heif",
+        "ief": "image/ief",
+        "jpeg": "image/jpeg",
+        "jpg": "image/jpeg",
+        "pict": "image/pict",
+        "pct": "image/pict",
+        "pic": "image/pict",
+        "png": "image/png",
+        "svg": "image/svg+xml",
+        "svgz": "image/svg+xml",
+        "tif": "image/tiff",
+        "tiff": "image/tiff",
+        "psd": "image/vnd.adobe.photoshop",
+        "djvu": "image/vnd.djvu",
+        "djv": "image/vnd.djvu",
+        "dwg": "image/vnd.dwg",
+        "dxf": "image/vnd.dxf",
+        "dds": "image/vnd.ms-dds",
+        "webp": "image/webp",
+        "3ds": "image/x-3ds",
+        "ras": "image/x-cmu-raster",
+        "ico": "image/x-icon",
+        "bmp": "image/x-ms-bmp",
+        "pnm": "image/x-portable-anymap",
+        "pbm": "image/x-portable-bitmap",
+        "pgm": "image/x-portable-graymap",
+        "ppm": "image/x-portable-pixmap",
+        "rgb": "image/x-rgb",
+        "tga": "image/x-tga",
+        "xbm": "image/x-xbitmap",
+        "xpm": "image/x-xpixmap",
+        "xwd": "image/x-xwindowdump",
+        "eml": "message/rfc822",
+        "mht": "message/rfc822",
+        "mhtml": "message/rfc822",
+        "nws": "message/rfc822",
+        "obj": "model/obj",
+        "stl": "model/stl",
+        "dae": "model/vnd.collada+xml",
+        "ics": "text/calendar",
+        "ifb": "text/calendar",
+        "css": "text/css",
+        "csv": "text/csv",
+        "html": "text/html",
+        "htm": "text/html",
+        "shtml": "text/html",
+        "markdown": "text/markdown",
+        "md": "text/markdown",
+        "txt": "text/plain",
+        "text": "text/plain",
+        "conf": "text/plain",
+        "def": "text/plain",
+        "list": "text/plain",
+        "log": "text/plain",
+        "in": "text/plain",
+        "ini": "text/plain",
+        "rtx": "text/richtext",
+        "rtf": "text/rtf",
+        "tsv": "text/tab-separated-values",
+        "c": "text/x-c",
+        "cc": "text/x-c",
+        "cxx": "text/x-c",
+        "cpp": "text/x-c",
+        "h": "text/x-c",
+        "hh": "text/x-c",
+        "dic": "text/x-c",
+        "java": "text/x-java-source",
+        "lua": "text/x-lua",
+        "py": "text/x-python",
+        "etx": "text/x-setext",
+        "sgm": "text/x-sgml",
+        "sgml": "text/x-sgml",
+        "vcf": "text/x-vcard",
+        "xml": "text/xml",
+        "xul": "text/xul",
+        "yaml": "text/yaml",
+        "yml": "text/yaml",
+        "ts": "video/mp2t",
+        "mp4": "video/mp4",
+        "mp4v": "video/mp4",
+        "mpg4": "video/mp4",
+        "mpeg": "video/mpeg",
+        "m1v": "video/mpeg",
+        "mpa": "video/mpeg",
+        "mpe": "video/mpeg",
+        "mpg": "video/mpeg",
+        "mov": "video/quicktime",
+        "qt": "video/quicktime",
+        "webm": "video/webm",
+        "flv": "video/x-flv",
+        "m4v": "video/x-m4v",
+        "asf": "video/x-ms-asf",
+        "asx": "video/x-ms-asf",
+        "vob": "video/x-ms-vob",
+        "wmv": "video/x-ms-wmv",
+        "avi": "video/x-msvideo",
+        "*": "video/x-sgi-movie"
+    }
+
     return {
-        getMimeByFilename(filename) {
-            try {
-                const arr = filename.split('.');
-                const suffix = arr[arr.length - 1].toLowerCase();
-                return {
-                    "cpl": "application/cpl+xml",
-                    "gpx": "application/gpx+xml",
-                    "gz": "application/gzip",
-                    "jar": "application/java-archive",
-                    "war": "application/java-archive",
-                    "ear": "application/java-archive",
-                    "class": "application/java-vm",
-                    "js": "application/javascript",
-                    "mjs": "application/javascript",
-                    "json": "application/json",
-                    "map": "application/json",
-                    "webmanifest": "application/manifest+json",
-                    "doc": "application/msword",
-                    "dot": "application/msword",
-                    "wiz": "application/msword",
-                    "bin": "application/octet-stream",
-                    "dms": "application/octet-stream",
-                    "lrf": "application/octet-stream",
-                    "mar": "application/octet-stream",
-                    "so": "application/octet-stream",
-                    "dist": "application/octet-stream",
-                    "distz": "application/octet-stream",
-                    "pkg": "application/octet-stream",
-                    "bpk": "application/octet-stream",
-                    "dump": "application/octet-stream",
-                    "elc": "application/octet-stream",
-                    "deploy": "application/octet-stream",
-                    "img": "application/octet-stream",
-                    "msp": "application/octet-stream",
-                    "msm": "application/octet-stream",
-                    "buffer": "application/octet-stream",
-                    "oda": "application/oda",
-                    "oxps": "application/oxps",
-                    "pdf": "application/pdf",
-                    "asc": "application/pgp-signature",
-                    "sig": "application/pgp-signature",
-                    "prf": "application/pics-rules",
-                    "p7c": "application/pkcs7-mime",
-                    "cer": "application/pkix-cert",
-                    "ai": "application/postscript",
-                    "eps": "application/postscript",
-                    "ps": "application/postscript",
-                    "apk": "application/vnd.android.package-archive",
-                    "m3u8": "application/vnd.apple.mpegurl",
-                    "pkpass": "application/vnd.apple.pkpass",
-                    "kml": "application/vnd.google-earth.kml+xml",
-                    "kmz": "application/vnd.google-earth.kmz",
-                    "cab": "application/vnd.ms-cab-compressed",
-                    "xls": "application/vnd.ms-excel",
-                    "xlm": "application/vnd.ms-excel",
-                    "xla": "application/vnd.ms-excel",
-                    "xlc": "application/vnd.ms-excel",
-                    "xlt": "application/vnd.ms-excel",
-                    "xlw": "application/vnd.ms-excel",
-                    "msg": "application/vnd.ms-outlook",
-                    "ppt": "application/vnd.ms-powerpoint",
-                    "pot": "application/vnd.ms-powerpoint",
-                    "ppa": "application/vnd.ms-powerpoint",
-                    "pps": "application/vnd.ms-powerpoint",
-                    "pwz": "application/vnd.ms-powerpoint",
-                    "mpp": "application/vnd.ms-project",
-                    "mpt": "application/vnd.ms-project",
-                    "xps": "application/vnd.ms-xpsdocument",
-                    "odb": "application/vnd.oasis.opendocument.database",
-                    "ods": "application/vnd.oasis.opendocument.spreadsheet",
-                    "odt": "application/vnd.oasis.opendocument.text",
-                    "osm": "application/vnd.openstreetmap.data+xml",
-                    "pptx": "application/vnd.openxmlformats-officedocument.presentationml.presentation",
-                    "xlsx": "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
-                    "docx": "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
-                    "pcap": "application/vnd.tcpdump.pcap",
-                    "cap": "application/vnd.tcpdump.pcap",
-                    "dmp": "application/vnd.tcpdump.pcap",
-                    "wpd": "application/vnd.wordperfect",
-                    "wasm": "application/wasm",
-                    "7z": "application/x-7z-compressed",
-                    "dmg": "application/x-apple-diskimage",
-                    "bcpio": "application/x-bcpio",
-                    "torrent": "application/x-bittorrent",
-                    "cbr": "application/x-cbr",
-                    "cba": "application/x-cbr",
-                    "cbt": "application/x-cbr",
-                    "cbz": "application/x-cbr",
-                    "cb7": "application/x-cbr",
-                    "vcd": "application/x-cdlink",
-                    "crx": "application/x-chrome-extension",
-                    "cpio": "application/x-cpio",
-                    "csh": "application/x-csh",
-                    "deb": "application/x-debian-package",
-                    "udeb": "application/x-debian-package",
-                    "dvi": "application/x-dvi",
-                    "arc": "application/x-freearc",
-                    "gtar": "application/x-gtar",
-                    "hdf": "application/x-hdf",
-                    "h5": "application/x-hdf5",
-                    "php": "application/x-httpd-php",
-                    "iso": "application/x-iso9660-image",
-                    "key": "application/x-iwork-keynote-sffkey",
-                    "numbers": "application/x-iwork-numbers-sffnumbers",
-                    "pages": "application/x-iwork-pages-sffpages",
-                    "latex": "application/x-latex",
-                    "run": "application/x-makeself",
-                    "mif": "application/x-mif",
-                    "lnk": "application/x-ms-shortcut",
-                    "mdb": "application/x-msaccess",
-                    "exe": "application/x-msdownload",
-                    "dll": "application/x-msdownload",
-                    "com": "application/x-msdownload",
-                    "bat": "application/x-msdownload",
-                    "msi": "application/x-msdownload",
-                    "pub": "application/x-mspublisher",
-                    "cdf": "application/x-netcdf",
-                    "nc": "application/x-netcdf",
-                    "pl": "application/x-perl",
-                    "pm": "application/x-perl",
-                    "prc": "application/x-pilot",
-                    "pdb": "application/x-pilot",
-                    "p12": "application/x-pkcs12",
-                    "pfx": "application/x-pkcs12",
-                    "ram": "application/x-pn-realaudio",
-                    "pyc": "application/x-python-code",
-                    "pyo": "application/x-python-code",
-                    "rar": "application/x-rar-compressed",
-                    "rpm": "application/x-redhat-package-manager",
-                    "sh": "application/x-sh",
-                    "shar": "application/x-shar",
-                    "swf": "application/x-shockwave-flash",
-                    "sql": "application/x-sql",
-                    "srt": "application/x-subrip",
-                    "sv4cpio": "application/x-sv4cpio",
-                    "sv4crc": "application/x-sv4crc",
-                    "gam": "application/x-tads",
-                    "tar": "application/x-tar",
-                    "tcl": "application/x-tcl",
-                    "tex": "application/x-tex",
-                    "roff": "application/x-troff",
-                    "t": "application/x-troff",
-                    "tr": "application/x-troff",
-                    "man": "application/x-troff-man",
-                    "me": "application/x-troff-me",
-                    "ms": "application/x-troff-ms",
-                    "ustar": "application/x-ustar",
-                    "src": "application/x-wais-source",
-                    "xpi": "application/x-xpinstall",
-                    "xhtml": "application/xhtml+xml",
-                    "xht": "application/xhtml+xml",
-                    "xsl": "application/xml",
-                    "rdf": "application/xml",
-                    "wsdl": "application/xml",
-                    "xpdl": "application/xml",
-                    "zip": "application/zip",
-                    "3gp": "audio/3gp",
-                    "3gpp": "audio/3gpp",
-                    "3g2": "audio/3gpp2",
-                    "3gpp2": "audio/3gpp2",
-                    "aac": "audio/aac",
-                    "adts": "audio/aac",
-                    "loas": "audio/aac",
-                    "ass": "audio/aac",
-                    "au": "audio/basic",
-                    "snd": "audio/basic",
-                    "mid": "audio/midi",
-                    "midi": "audio/midi",
-                    "kar": "audio/midi",
-                    "rmi": "audio/midi",
-                    "mpga": "audio/mpeg",
-                    "mp2": "audio/mpeg",
-                    "mp2a": "audio/mpeg",
-                    "mp3": "audio/mpeg",
-                    "m2a": "audio/mpeg",
-                    "m3a": "audio/mpeg",
-                    "oga": "audio/ogg",
-                    "ogg": "audio/ogg",
-                    "spx": "audio/ogg",
-                    "opus": "audio/opus",
-                    "aif": "audio/x-aiff",
-                    "aifc": "audio/x-aiff",
-                    "aiff": "audio/x-aiff",
-                    "flac": "audio/x-flac",
-                    "m4a": "audio/x-m4a",
-                    "m3u": "audio/x-mpegurl",
-                    "wma": "audio/x-ms-wma",
-                    "ra": "audio/x-pn-realaudio",
-                    "wav": "audio/x-wav",
-                    "otf": "font/otf",
-                    "ttf": "font/ttf",
-                    "woff": "font/woff",
-                    "woff2": "font/woff2",
-                    "emf": "image/emf",
-                    "gif": "image/gif",
-                    "heic": "image/heic",
-                    "heif": "image/heif",
-                    "ief": "image/ief",
-                    "jpeg": "image/jpeg",
-                    "jpg": "image/jpeg",
-                    "pict": "image/pict",
-                    "pct": "image/pict",
-                    "pic": "image/pict",
-                    "png": "image/png",
-                    "svg": "image/svg+xml",
-                    "svgz": "image/svg+xml",
-                    "tif": "image/tiff",
-                    "tiff": "image/tiff",
-                    "psd": "image/vnd.adobe.photoshop",
-                    "djvu": "image/vnd.djvu",
-                    "djv": "image/vnd.djvu",
-                    "dwg": "image/vnd.dwg",
-                    "dxf": "image/vnd.dxf",
-                    "dds": "image/vnd.ms-dds",
-                    "webp": "image/webp",
-                    "3ds": "image/x-3ds",
-                    "ras": "image/x-cmu-raster",
-                    "ico": "image/x-icon",
-                    "bmp": "image/x-ms-bmp",
-                    "pnm": "image/x-portable-anymap",
-                    "pbm": "image/x-portable-bitmap",
-                    "pgm": "image/x-portable-graymap",
-                    "ppm": "image/x-portable-pixmap",
-                    "rgb": "image/x-rgb",
-                    "tga": "image/x-tga",
-                    "xbm": "image/x-xbitmap",
-                    "xpm": "image/x-xpixmap",
-                    "xwd": "image/x-xwindowdump",
-                    "eml": "message/rfc822",
-                    "mht": "message/rfc822",
-                    "mhtml": "message/rfc822",
-                    "nws": "message/rfc822",
-                    "obj": "model/obj",
-                    "stl": "model/stl",
-                    "dae": "model/vnd.collada+xml",
-                    "ics": "text/calendar",
-                    "ifb": "text/calendar",
-                    "css": "text/css",
-                    "csv": "text/csv",
-                    "html": "text/html",
-                    "htm": "text/html",
-                    "shtml": "text/html",
-                    "markdown": "text/markdown",
-                    "md": "text/markdown",
-                    "txt": "text/plain",
-                    "text": "text/plain",
-                    "conf": "text/plain",
-                    "def": "text/plain",
-                    "list": "text/plain",
-                    "log": "text/plain",
-                    "in": "text/plain",
-                    "ini": "text/plain",
-                    "rtx": "text/richtext",
-                    "rtf": "text/rtf",
-                    "tsv": "text/tab-separated-values",
-                    "c": "text/x-c",
-                    "cc": "text/x-c",
-                    "cxx": "text/x-c",
-                    "cpp": "text/x-c",
-                    "h": "text/x-c",
-                    "hh": "text/x-c",
-                    "dic": "text/x-c",
-                    "java": "text/x-java-source",
-                    "lua": "text/x-lua",
-                    "py": "text/x-python",
-                    "etx": "text/x-setext",
-                    "sgm": "text/x-sgml",
-                    "sgml": "text/x-sgml",
-                    "vcf": "text/x-vcard",
-                    "xml": "text/xml",
-                    "xul": "text/xul",
-                    "yaml": "text/yaml",
-                    "yml": "text/yaml",
-                    "ts": "video/mp2t",
-                    "mp4": "video/mp4",
-                    "mp4v": "video/mp4",
-                    "mpg4": "video/mp4",
-                    "mpeg": "video/mpeg",
-                    "m1v": "video/mpeg",
-                    "mpa": "video/mpeg",
-                    "mpe": "video/mpeg",
-                    "mpg": "video/mpeg",
-                    "mov": "video/quicktime",
-                    "qt": "video/quicktime",
-                    "webm": "video/webm",
-                    "flv": "video/x-flv",
-                    "m4v": "video/x-m4v",
-                    "asf": "video/x-ms-asf",
-                    "asx": "video/x-ms-asf",
-                    "vob": "video/x-ms-vob",
-                    "wmv": "video/x-ms-wmv",
-                    "avi": "video/x-msvideo",
-                    "*": "video/x-sgi-movie",
-                }[suffix] || '';
-            } catch (e) {
-                console.error(e);
-                return '';
+        async guessMimeByFilename(filename) {
+            const split = filename.split('.');
+            if (split.length === 1) {
+                // Filename does not include suffix
+                return "";
             }
+            const suffix = split[split.length - 1].toLowerCase();
+            return suffixToMimeMap[suffix] || "";
+        },
+        async addMissingMimeTypesToFiles(files) {
+            // if filetype is empty guess via suffix otherwise leave unchanged
+            for (let i = 0; i < files.length; i++) {
+                if (!files[i].type) {
+                    files[i] = new File([files[i]], files[i].name, {type: await mime.guessMimeByFilename(files[i].name) || ""});
+                }
+            }
+            return files;
         }
     };