diff --git a/test/requirements.txt b/test/requirements.txt
index b3b14651bc5..0723100bd68 100644
--- a/test/requirements.txt
+++ b/test/requirements.txt
@@ -7,6 +7,8 @@ parameterized>=0.6.1                    # BSD
 pexpect                                 # ISC
 psutil                                  # BSD
 pycodestyle                             # MIT (Expat license)       https://pypi.org/project/pycodestyle/
+# used by syslog_rfc5424_parser
+pyparsing<2.3.1                         # MIT
 scapy==2.4.0; python_version >= '2.7' or python_version >= '3.4'    # GPL2  https://github.com/secdev/scapy/blob/master/LICENSE
 six                                     # MIT
 subprocess32                            # PSF