diff --git a/moto/polly/models.py b/moto/polly/models.py
index d97399358..d28abd409 100644
--- a/moto/polly/models.py
+++ b/moto/polly/models.py
@@ -42,7 +42,7 @@ class Lexicon(BaseModel):
                     self.language_code = value
 
         except Exception as err:
-            raise ValueError("Failure parsing XML: {0}".format(err))
+            raise ValueError(f"Failure parsing XML: {err}")
 
     def to_dict(self):
         return {
@@ -57,7 +57,7 @@ class Lexicon(BaseModel):
         }
 
     def __repr__(self):
-        return "<Lexicon {0}>".format(self.name)
+        return f"<Lexicon {self.name}>"
 
 
 class PollyBackend(BaseBackend):
diff --git a/moto/polly/responses.py b/moto/polly/responses.py
index f0f7d8b77..6b4532ac3 100644
--- a/moto/polly/responses.py
+++ b/moto/polly/responses.py
@@ -39,11 +39,10 @@ class PollyResponse(BaseResponse):
         language_code = self._get_param("LanguageCode")
 
         if language_code is not None and language_code not in LANGUAGE_CODES:
+            all_codes = ", ".join(LANGUAGE_CODES)
             msg = (
-                "1 validation error detected: Value '{0}' at 'languageCode' failed to satisfy constraint: "
-                "Member must satisfy enum value set: [{1}]".format(
-                    language_code, ", ".join(LANGUAGE_CODES)
-                )
+                f"1 validation error detected: Value '{language_code}' at 'languageCode' failed to satisfy constraint: "
+                f"Member must satisfy enum value set: [{all_codes}]"
             )
             return msg, dict(status=400)
 
@@ -170,9 +169,8 @@ class PollyResponse(BaseResponse):
         if "VoiceId" not in self.json:
             return self._error("MissingParameter", "Missing parameter VoiceId")
         if self.json["VoiceId"] not in VOICE_IDS:
-            return self._error(
-                "InvalidParameterValue", "Not one of {0}".format(", ".join(VOICE_IDS))
-            )
+            all_voices = ", ".join(VOICE_IDS)
+            return self._error("InvalidParameterValue", f"Not one of {all_voices}")
         args["voice_id"] = self.json["VoiceId"]
 
         # More validation
diff --git a/moto/polly/utils.py b/moto/polly/utils.py
index c13404109..a0de8713a 100644
--- a/moto/polly/utils.py
+++ b/moto/polly/utils.py
@@ -1,2 +1,2 @@
 def make_arn_for_lexicon(account_id, name, region_name):
-    return "arn:aws:polly:{0}:{1}:lexicon/{2}".format(region_name, account_id, name)
+    return f"arn:aws:polly:{region_name}:{account_id}:lexicon/{name}"