diff --git a/src/display/content_disposition.js b/src/display/content_disposition.js
index af180181e4de4..0dec00c886d68 100644
--- a/src/display/content_disposition.js
+++ b/src/display/content_disposition.js
@@ -107,7 +107,11 @@ function getFilenameFromContentDispositionHeader(contentDisposition) {
   function fixupEncoding(value) {
     if (needsEncodingFixup && /[\x80-\xff]/.test(value)) {
       // Maybe multi-byte UTF-8.
-      return textdecode('utf-8', value);
+      value = textdecode('utf-8', value);
+      if (needsEncodingFixup) {
+        // Try iso-8859-1 encoding.
+        value = textdecode('iso-8859-1', value);
+      }
     }
     return value;
   }
@@ -209,10 +213,10 @@ function getFilenameFromContentDispositionHeader(contentDisposition) {
           return textdecode(charset, text);
         } // else encoding is b or B - base64 (RFC 2047 section 4.1)
         try {
-          return atob(text);
+          text = atob(text);
         } catch (e) {
-          return text;
         }
+        return textdecode(charset, text);
       });
   }