--- a/browser/components/downloads/DownloadsCommon.jsm
+++ b/browser/components/downloads/DownloadsCommon.jsm
@@ -1216,17 +1216,24 @@ DownloadsIndicatorDataCtor.prototype = {
    */
   _refreshProperties() {
     let summary =
       DownloadsCommon.summarizeDownloads(this._activeDownloads());
 
     // Determine if the indicator should be shown or get attention.
     this._hasDownloads = (this._itemCount > 0);
 
-    this._percentComplete = summary.percentComplete;
+    // Always show a progress bar if there are downloads in progress.
+    if (summary.percentComplete >= 0) {
+      this._percentComplete = summary.percentComplete;
+    } else if (summary.numDownloading > 0) {
+      this._percentComplete = 0;
+    } else {
+      this._percentComplete = -1;
+    }
   }
 };
 
 XPCOMUtils.defineLazyGetter(this, "PrivateDownloadsIndicatorData", function() {
   return new DownloadsIndicatorDataCtor(true);
 });
 
 XPCOMUtils.defineLazyGetter(this, "DownloadsIndicatorData", function() {