diff --git a/Pipfile b/Pipfile
index e8630d6..0b8d051 100644
--- a/Pipfile
+++ b/Pipfile
@@ -13,4 +13,4 @@ flake8 = "*"
 mypy = "*"
 
 [requires]
-python_version = "3.8"
+python_version = "3.9"
diff --git a/subscriber.py b/subscriber.py
index 57ff1d3..a97a064 100644
--- a/subscriber.py
+++ b/subscriber.py
@@ -29,14 +29,15 @@ def build_groups_list(
     pattern: Optional[str] = None,
     prefix: Optional[str] = None,
 ):
-    # filter out the log groups based on the names, pattern, and prefix provided in the environment variables
-    groups = []
     # ensure filter params have correct values
-    if pattern == "":
+    if not names:
+        names = None
+    if not pattern:
         pattern = None
-    elif prefix == "":
+    if not prefix:
         prefix = None
-
+    # filter out the log groups based on the names, pattern, and prefix provided in the environment variables
+    groups = []
     for g in all_groups:
         group = {"name": g["logGroupName"].strip(), "arn": g["arn"]}
         if names is None and pattern is None and prefix is None:
diff --git a/unsubscriber.py b/unsubscriber.py
index 211ddef..3a9a978 100644
--- a/unsubscriber.py
+++ b/unsubscriber.py
@@ -30,9 +30,11 @@ def build_groups_list(
     prefix: Optional[str] = None,
 ):
     # ensure filter params have correct values
-    if pattern == "":
+    if not names:
+        names = None
+    if not pattern:
         pattern = None
-    elif prefix == "":
+    if not prefix:
         prefix = None
     # filter out the log groups based on the names, pattern, and prefix provided in the environment variables
     groups = []