diff --git a/changes/4155-aminalaee.md b/changes/4155-aminalaee.md
new file mode 100644
index 0000000000..8eae2e1c3f
--- /dev/null
+++ b/changes/4155-aminalaee.md
@@ -0,0 +1 @@
+Fix JSON schema for `set` and `frozenset` when they include default values.
diff --git a/docs/build/schema_mapping.py b/docs/build/schema_mapping.py
index c9b6c018fd..96c7b74a01 100755
--- a/docs/build/schema_mapping.py
+++ b/docs/build/schema_mapping.py
@@ -74,6 +74,13 @@
         'JSON Schema Validation',
         ''
     ],
+    [
+        'frozenset',
+        'array',
+        {'items': {}, 'uniqueItems': True},
+        'JSON Schema Validation',
+        ''
+    ],
     [
         'List[str]',
         'array',
diff --git a/pydantic/schema.py b/pydantic/schema.py
index c0e032f81e..593cab5ad5 100644
--- a/pydantic/schema.py
+++ b/pydantic/schema.py
@@ -77,7 +77,7 @@
     is_none_type,
     is_union,
 )
-from .utils import ROOT_KEY, get_model, lenient_issubclass, sequence_like
+from .utils import ROOT_KEY, get_model, lenient_issubclass
 
 if TYPE_CHECKING:
     from .dataclasses import Dataclass
@@ -970,7 +970,7 @@ def encode_default(dft: Any) -> Any:
         return dft.value
     elif isinstance(dft, (int, float, str)):
         return dft
-    elif sequence_like(dft):
+    elif isinstance(dft, (list, tuple)):
         t = dft.__class__
         seq_args = (encode_default(v) for v in dft)
         return t(*seq_args) if is_namedtuple(t) else t(seq_args)
diff --git a/tests/test_schema.py b/tests/test_schema.py
index b1bb7fd80f..f8db3129ab 100644
--- a/tests/test_schema.py
+++ b/tests/test_schema.py
@@ -530,6 +530,7 @@ def test_set():
     class Model(BaseModel):
         a: Set[int]
         b: set
+        c: set = {1}
 
     assert Model.schema() == {
         'title': 'Model',
@@ -537,6 +538,7 @@ class Model(BaseModel):
         'properties': {
             'a': {'title': 'A', 'type': 'array', 'uniqueItems': True, 'items': {'type': 'integer'}},
             'b': {'title': 'B', 'type': 'array', 'items': {}, 'uniqueItems': True},
+            'c': {'title': 'C', 'type': 'array', 'items': {}, 'default': [1], 'uniqueItems': True},
         },
         'required': ['a', 'b'],
     }
@@ -2187,13 +2189,13 @@ class Model(BaseModel):
         'properties': {
             'a': {
                 'title': 'A',
-                'default': frozenset({1, 2, 3}),
+                'default': [1, 2, 3],
                 'type': 'array',
                 'items': {'type': 'integer'},
                 'uniqueItems': True,
             },
-            'b': {'title': 'B', 'default': frozenset({1, 2, 3}), 'type': 'array', 'items': {}, 'uniqueItems': True},
-            'c': {'title': 'C', 'default': frozenset({1, 2, 3}), 'type': 'array', 'items': {}, 'uniqueItems': True},
+            'b': {'title': 'B', 'default': [1, 2, 3], 'type': 'array', 'items': {}, 'uniqueItems': True},
+            'c': {'title': 'C', 'default': [1, 2, 3], 'type': 'array', 'items': {}, 'uniqueItems': True},
             'd': {'title': 'D', 'type': 'array', 'items': {}, 'uniqueItems': True},
         },
         'required': ['d'],