diff --git a/gen-go-code.py b/gen-go-code.py
index 711afcb07..0678275d7 100755
--- a/gen-go-code.py
+++ b/gen-go-code.py
@@ -562,6 +562,17 @@ def generate_readline_actions() -> str:
     ''')
 
 
+def generate_mimetypes() -> str:
+    import mimetypes
+    if not mimetypes.inited:
+        mimetypes.init()
+    ans = ['package utils', 'import "sync"', 'var only_once sync.Once', 'var builtin_types_map map[string]string', 'func set_builtins() {', 'builtin_types_map = map[string]string{',]
+    for k, v in mimetypes.types_map.items():
+        ans.append(f'  "{serialize_as_go_string(k)}": "{serialize_as_go_string(v)}",')
+    ans.append('}}')
+    return '\n'.join(ans)
+
+
 def main() -> None:
     with replace_if_needed('constants_generated.go') as f:
         f.write(generate_constants())
@@ -571,6 +582,8 @@ def main() -> None:
         f.write(generate_readline_actions())
     with replace_if_needed('tools/tui/spinners_generated.go') as f:
         f.write(generate_spinners())
+    with replace_if_needed('tools/utils/mimetypes_generated.go') as f:
+        f.write(generate_mimetypes())
     update_completion()
     update_at_commands()
     kitten_clis()
diff --git a/tools/utils/mimetypes.go b/tools/utils/mimetypes.go
index a70616c5c..a5e7db410 100644
--- a/tools/utils/mimetypes.go
+++ b/tools/utils/mimetypes.go
@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"mime"
 	"path/filepath"
+	"strings"
 )
 
 var _ = fmt.Print
@@ -14,7 +15,14 @@ func GuessMimeType(filename string) string {
 	ext := filepath.Ext(filename)
 	mime_with_parameters := mime.TypeByExtension(ext)
 	if mime_with_parameters == "" {
-		return mime_with_parameters
+		only_once.Do(set_builtins)
+		mime_with_parameters = builtin_types_map[ext]
+		if mime_with_parameters == "" {
+			mime_with_parameters = builtin_types_map[strings.ToLower(ext)]
+			if mime_with_parameters == "" {
+				return ""
+			}
+		}
 	}
 	ans, _, err := mime.ParseMediaType(mime_with_parameters)
 	if err != nil {