diff --git a/.mailmap b/.mailmap
index 17c44ef97b1..71a84fdefc6 100644
--- a/.mailmap
+++ b/.mailmap
@@ -1,4 +1,4 @@
-# FORMAT: <proper-name>  <proper-email>  <commit-name>  <commit-email>   
+# FORMAT: <proper-name>  <proper-email>  <commit-name>  <commit-email>
 # Omit commit-name or commit-email if same as proper
 
 Alex Reinecke              <alex.reinecke@nrlmry.navy.mil>      P. A. Reinecke
@@ -52,6 +52,8 @@ Tim Whitcomb               <tim.whitcomb@nrlmry.navy.mil>
 Tim Whitcomb               <tim.whitcomb@nrlmry.navy.mil>       trwhitcomb          <twhitcomb@gmail.com>
 Tomek Trzeciak             <tomasz.trzeciak@metoffice.gov.uk>                       <TomekTrzeciak@users.noreply.github.com>
 Tomek Trzeciak             <tomasz.trzeciak@metoffice.gov.uk>   TomekTrzeciak       <tomasz.trzeciak@metoffice.gov.uk>
-github-actions[bot]        <github-actions@noreply.github.com>                      <41898282+github-actions[bot]@users.noreply.github.com> 
+Utheri Wagura              <utheriwagura@gmail.com>
+Utheri Wagura              <36386988+uwagura@users.noreply.github.com>
+github-actions[bot]        <github-actions@noreply.github.com>                      <41898282+github-actions[bot]@users.noreply.github.com>
 github-actions[bot]        <github-actions@noreply.github.com>  GitHub Action
 Diquan Jabbour             <165976689+Diquan-BOM@users.noreply.github.com>
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 30e81f26f93..a4e77fd82a7 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -95,6 +95,7 @@ requests_).
  - Mark Dawson
  - Diquan Jabbour
  - Shixian Sheng
+ - Utheri Wagura
 <!-- end-shortlog -->
 
 (All contributors are identifiable with email addresses in the git version
diff --git a/changes.d/6332.fix.md b/changes.d/6332.fix.md
new file mode 100644
index 00000000000..6fa937c4d33
--- /dev/null
+++ b/changes.d/6332.fix.md
@@ -0,0 +1 @@
+ Fixes unformatted string
diff --git a/cylc/flow/graph_parser.py b/cylc/flow/graph_parser.py
index efbce16fb36..64665c96983 100644
--- a/cylc/flow/graph_parser.py
+++ b/cylc/flow/graph_parser.py
@@ -643,7 +643,7 @@ def _proc_dep_pair(
                     # Not a family.
                     if trig in self.__class__.fam_to_mem_trigger_map:
                         raise GraphParseError(
-                            "family trigger on non-family namespace {expr}")
+                            f"family trigger on non-family namespace {expr}")
 
             # remove '?' from expr (not needed in logical trigger evaluation)
             expr = re.sub(self.__class__._RE_OPT, '', expr)