diff --git a/contrib/buildbot/server.py b/contrib/buildbot/server.py
--- a/contrib/buildbot/server.py
+++ b/contrib/buildbot/server.py
@@ -154,7 +154,7 @@
                     return repl
 
                 line = re.sub(
-                    r'PR(\d{3}\d+)',
+                    r'PR[ #]?(\d{3}\d+)',
                     replacePRWithLink(
                         'https://github.com/bitcoin/bitcoin/pull'),
                     line)
diff --git a/contrib/buildbot/test/test_endpoint_backportcheck.py b/contrib/buildbot/test/test_endpoint_backportcheck.py
--- a/contrib/buildbot/test/test_endpoint_backportcheck.py
+++ b/contrib/buildbot/test/test_endpoint_backportcheck.py
@@ -70,6 +70,7 @@
                 'summary': "This is a test summary\n"
                 # Bitcoin Core links
                 "Backport of Core PR2345 and PR34567\n"
+                "Backports with optional separators PR 2345 and PR#34567\n"
                 "PR6789 outside of a code block `PR4567 inside a code block`\n"
                 "```PR4567 in a single-line code block```\n"
                 "```\nPR4567 in a multi-line code block\n```\n"
@@ -96,6 +97,8 @@
             # Bitcoin Core links
             "Backport of Core [[https://github.com/bitcoin/bitcoin/pull/2345 | PR2345]] and "
             "[[https://github.com/bitcoin/bitcoin/pull/34567 | PR34567]]\n"
+            "Backports with optional separators [[https://github.com/bitcoin/bitcoin/pull/2345 | PR2345]] and "
+            "[[https://github.com/bitcoin/bitcoin/pull/34567 | PR34567]]\n"
             "[[https://github.com/bitcoin/bitcoin/pull/6789 | PR6789]] outside of a code block `PR4567 inside a code block`\n"
             "```PR4567 in a single-line code block```\n"
             "```\nPR4567 in a multi-line code block\n```\n"