diff --git a/IPython/core/application.py b/IPython/core/application.py
index 2aa0f10..10df040 100644
--- a/IPython/core/application.py
+++ b/IPython/core/application.py
@@ -400,7 +400,7 @@ class BaseIPythonApplication(Application):
                     self.log.fatal("Profile %r not found."%self.profile)
                     self.exit(1)
             else:
-                self.log.debug(f"Using existing profile dir: {p.location!r}")
+                self.log.debug("Using existing profile dir: %r", p.location)
         else:
             location = self.config.ProfileDir.location
             # location is fully specified
@@ -420,7 +420,7 @@ class BaseIPythonApplication(Application):
                     self.log.fatal("Profile directory %r not found."%location)
                     self.exit(1)
             else:
-                self.log.debug(f"Using existing profile dir: {p.location!r}")
+                self.log.debug("Using existing profile dir: %r", p.location)
             # if profile_dir is specified explicitly, set profile name
             dir_name = os.path.basename(p.location)
             if dir_name.startswith('profile_'):