diff --git a/fmriprep/interfaces/reports.py b/fmriprep/interfaces/reports.py
index d5d5b4573..bcc81416c 100644
--- a/fmriprep/interfaces/reports.py
+++ b/fmriprep/interfaces/reports.py
@@ -169,10 +169,9 @@ def _generate_segment(self):
         if counts:
             header = '\t\t<ul class="elem-desc">'
             footer = '\t\t</ul>'
+            s = '' if n_runs == 1 else 's'
             lines = [
-                '\t\t\t<li>Task: {task_id} ({n_runs:d} run{s})</li>'.format(
-                    task_id=task_id, n_runs=n_runs, s='' if n_runs == 1 else 's'
-                )
+                f'\t\t\t<li>Task: {task_id} ({n_runs:d} run{s})</li>'
                 for task_id, n_runs in sorted(counts.items())
             ]
             tasks = '\n'.join([header] + lines + [footer])
diff --git a/fmriprep/workflows/base.py b/fmriprep/workflows/base.py
index 6883bbf14..0628d48d7 100644
--- a/fmriprep/workflows/base.py
+++ b/fmriprep/workflows/base.py
@@ -215,12 +215,10 @@ def init_single_subject_wf(subject_id: str):
     anat_only = config.workflow.anat_only
     # Make sure we always go through these two checks
     if not anat_only and not subject_data['bold']:
-        task_id = config.execution.task_id
+        task_id = config.execution.task_id or '<all>'
         raise RuntimeError(
-            'No BOLD images found for participant {} and task {}. '
-            'All workflows require BOLD images.'.format(
-                subject_id, task_id if task_id else '<all>'
-            )
+            f'No BOLD images found for participant {subject_id} and '
+            f'task {task_id}. All workflows require BOLD images.'
         )
 
     bold_runs = [