diff --git a/cid/cid.py b/cid/cid.py
index 7a604b6..702b1d6 100644
--- a/cid/cid.py
+++ b/cid/cid.py
@@ -242,7 +242,7 @@ def buffer(self) -> bytes:
         """
         return b"".join([bytes([self.version]), multicodec.add_prefix(self.codec, self.multihash)])
 
-    def encode(self, encoding: str | None = "base58btc") -> bytes:
+    def encode(self, encoding: str | None = "base32") -> bytes:
         """
         Encoded version of the raw representation
 
diff --git a/newsfragments/66.breaking.rst b/newsfragments/66.breaking.rst
new file mode 100644
index 0000000..831d882
--- /dev/null
+++ b/newsfragments/66.breaking.rst
@@ -0,0 +1 @@
+Change CIDv1.encode() default encoding to base32 to conform with CID specification.
diff --git a/tests/test_cid.py b/tests/test_cid.py
index d79fc6b..486330d 100644
--- a/tests/test_cid.py
+++ b/tests/test_cid.py
@@ -69,8 +69,8 @@ def test_buffer(self, cid):
         assert buffer[1:] == multicodec.add_prefix(self.TEST_CODEC, cid.multihash)
 
     def test_encode_default(self, cid):
-        """#encode defaults to base58btc encoding"""
-        assert cid.encode() == b"zdj7WhuEjrB52m1BisYCtmjH1hSKa7yZ3jEZ9JcXaFRD51wVz"
+        """#encode defaults to base32 encoding"""
+        assert cid.encode() == b"bafybeifzjut3te2nhyekklss27nh3k72ysco7y32koao5eei66wof36n5e"
 
     @pytest.mark.parametrize("codec", ENCODINGS)
     def test_encode_encoding(self, cid, codec):