diff --git a/CHANGES b/CHANGES
index b7f125b47..841273d5f 100644
--- a/CHANGES
+++ b/CHANGES
@@ -39,6 +39,7 @@ Bugs fixed
 * #4149: Documentation: Help choosing :confval:`latex_engine`
 * #4090: [doc] :confval:`latex_additional_files` with extra LaTeX macros should
   not use ``.tex`` extension
+* Failed to convert reST parser error to warning (refs: #4132)
 
 Testing
 --------
diff --git a/sphinx/util/docutils.py b/sphinx/util/docutils.py
index c984bcfaf..a8df9c59d 100644
--- a/sphinx/util/docutils.py
+++ b/sphinx/util/docutils.py
@@ -26,8 +26,7 @@ from sphinx.locale import __
 from sphinx.util import logging
 
 logger = logging.getLogger(__name__)
-report_re = re.compile('^(.+?:(?:\\d+)?): \\((DEBUG|INFO|WARNING|ERROR|SEVERE)/(\\d+)?\\) '
-                       '(.+?)\n?$')
+report_re = re.compile('^(.+?:(?:\\d+)?): \\((DEBUG|INFO|WARNING|ERROR|SEVERE)/(\\d+)?\\) ')
 
 if False:
     # For type annotation
@@ -162,7 +161,8 @@ class WarningStream(object):
         if not matched:
             logger.warning(text.rstrip("\r\n"))
         else:
-            location, type, level, message = matched.groups()
+            location, type, level = matched.groups()
+            message = report_re.sub('', text).rstrip()
             logger.log(type, message, location=location)