diff --git a/youtube_dl/downloader/common.py b/youtube_dl/downloader/common.py
index f39db58f6..1dba9f49a 100644
--- a/youtube_dl/downloader/common.py
+++ b/youtube_dl/downloader/common.py
@@ -115,6 +115,10 @@ class FileDownloader(object):
             return '%10s' % '---b/s'
         return '%10s' % ('%s/s' % format_bytes(speed))
 
+    @staticmethod
+    def format_retries(retries):
+        return 'inf' if retries == float('inf') else '%.0f' % retries
+
     @staticmethod
     def best_block_size(elapsed_time, bytes):
         new_min = max(bytes / 2.0, 1.0)
@@ -297,7 +301,9 @@ class FileDownloader(object):
 
     def report_retry(self, count, retries):
         """Report retry in case of HTTP error 5xx"""
-        self.to_screen('[download] Got server HTTP error. Retrying (attempt %d of %.0f)...' % (count, retries))
+        self.to_screen(
+            '[download] Got server HTTP error. Retrying (attempt %d of %s)...'
+            % (count, self.format_retries(retries)))
 
     def report_file_already_downloaded(self, file_name):
         """Report file has already been fully downloaded."""
diff --git a/youtube_dl/downloader/fragment.py b/youtube_dl/downloader/fragment.py
index df66c35f0..c2671e6d2 100644
--- a/youtube_dl/downloader/fragment.py
+++ b/youtube_dl/downloader/fragment.py
@@ -23,8 +23,8 @@ class FragmentFD(FileDownloader):
 
     def report_retry_fragment(self, fragment_name, count, retries):
         self.to_screen(
-            '[download] Got server HTTP error. Retrying fragment %s (attempt %d of %.0f)...'
-            % (fragment_name, count, retries))
+            '[download] Got server HTTP error. Retrying fragment %s (attempt %d of %s)...'
+            % (fragment_name, count, self.format_retries(retries)))
 
     def _prepare_and_start_frag_download(self, ctx):
         self._prepare_frag_download(ctx)