diff --git a/betterproto2/src/betterproto2/__init__.py b/betterproto2/src/betterproto2/__init__.py
index d881ff53..d7174c1a 100644
--- a/betterproto2/src/betterproto2/__init__.py
+++ b/betterproto2/src/betterproto2/__init__.py
@@ -1270,7 +1270,7 @@ def is_set(self, name: str) -> bool:
         :class:`bool`
             `True` if field has been set, otherwise `False`.
         """
-        return self.__getattribute__(name) is not self._get_field_default(name)
+        return self.__getattribute__(name) != self._get_field_default(name)
 
     @classmethod
     def _validate_field_groups(cls, values):
diff --git a/betterproto2/tests/test_features.py b/betterproto2/tests/test_features.py
index 0c5a4e16..bbb37844 100644
--- a/betterproto2/tests/test_features.py
+++ b/betterproto2/tests/test_features.py
@@ -430,8 +430,10 @@ def test_is_set():
 
     assert not MsgE().is_set("bool_field")
     assert not MsgE().is_set("int_field")
+    assert not MsgE().is_set("str_field")
     assert MsgE(bool_field=True).is_set("bool_field")
     assert MsgE(bool_field=True, int_field=0).is_set("int_field")
+    assert MsgE(str_field=["a", "b", "c"]).is_set("str_field")
 
 
 def test_equality_comparison():
diff --git a/betterproto2_compiler/tests/inputs/features/features.proto b/betterproto2_compiler/tests/inputs/features/features.proto
index 65048850..760abca8 100644
--- a/betterproto2_compiler/tests/inputs/features/features.proto
+++ b/betterproto2_compiler/tests/inputs/features/features.proto
@@ -104,4 +104,5 @@ message MsgD {
 message MsgE {
     bool bool_field = 1;
     optional int32 int_field = 2;
+    repeated string str_field = 3;
 }
\ No newline at end of file