diff --git a/pyquarantine/cli.py b/pyquarantine/cli.py
index 14d9828..4f0fa10 100644
--- a/pyquarantine/cli.py
+++ b/pyquarantine/cli.py
@@ -28,7 +28,7 @@ def _get_quarantine(quarantines, name):
     try:
         quarantine = next((q for q in quarantines if q.name == name))
     except StopIteration:
-        raise RuntimeError(f"invalid quarantine 'name'")
+        raise RuntimeError("invalid quarantine 'name'")
     return quarantine
 
 
diff --git a/pyquarantine/notifications.py b/pyquarantine/notifications.py
index d6751ca..4b458a2 100644
--- a/pyquarantine/notifications.py
+++ b/pyquarantine/notifications.py
@@ -212,7 +212,7 @@ class EMailNotification(BaseNotification):
                 raise RuntimeError(f"error reading image: {e}")
             else:
                 filename = basename(img_path)
-                img.add_header(f"Content-ID", f"<{filename}>")
+                img.add_header("Content-ID", f"<{filename}>")
                 self.embedded_imgs.append(img)
 
     def get_email_body_soup(self, qid, msg):