diff --git a/image_prediction/transformer/transformers/response.py b/image_prediction/transformer/transformers/response.py
index 91244c9..7c2b326 100644
--- a/image_prediction/transformer/transformers/response.py
+++ b/image_prediction/transformer/transformers/response.py
@@ -4,7 +4,7 @@ import os
 from functools import lru_cache
 from operator import itemgetter
 
-from funcy import filter, juxt, first, rest, compose
+from funcy import first
 
 from image_prediction.config import CONFIG
 from image_prediction.exceptions import ParsingError
@@ -131,16 +131,14 @@ def build_image_info(data: dict) -> dict:
 @lru_cache(maxsize=None)
 def parse_env_var(prefix, table=None):
     table = table or os.environ
-    head, tail = juxt(first, compose(list, rest))(filter(prefix, table))
-    if not head:
-        logger.warning(f"Found no environment variable with prefix '{prefix}'.")
-    elif tail:
-        logger.warning(f"Found multiple candidates for environment variable with prefix '{prefix}'.")
-    else:
+    head = first(filter(lambda s: s == prefix, table))
+    if head:
         try:
             return parse_env_var_value(table[head])
         except ParsingError as err:
             logger.warning(err)
+    else:
+        return None
 
 
 def parse_env_var_value(env_var_value):