diff --git a/google/cloud/storage/client.py b/google/cloud/storage/client.py
index fd29abe9c..e522052da 100644
--- a/google/cloud/storage/client.py
+++ b/google/cloud/storage/client.py
@@ -1090,7 +1090,7 @@ def generate_signed_post_policy_v4(
                 "x-goog-credential": x_goog_credential,
                 "x-goog-date": timestamp,
                 "x-goog-signature": signature,
-                "policy": str_to_sign,
+                "policy": str_to_sign.decode("utf-8"),
             }
         )
         # designate URL
diff --git a/tests/unit/test_client.py b/tests/unit/test_client.py
index 600e11943..e42321089 100644
--- a/tests/unit/test_client.py
+++ b/tests/unit/test_client.py
@@ -1606,7 +1606,7 @@ def test_get_signed_policy_v4(self):
         BUCKET_NAME = "bucket-name"
         BLOB_NAME = "object-name"
         EXPECTED_SIGN = "5369676e61747572655f6279746573"
-        EXPECTED_POLICY = b"eyJjb25kaXRpb25zIjpbeyJidWNrZXQiOiJidWNrZXQtbmFtZSJ9LHsiYWNsIjoicHJpdmF0ZSJ9LFsic3RhcnRzLXdpdGgiLCIkQ29udGVudC1UeXBlIiwidGV4dC9wbGFpbiJdLHsiYnVja2V0IjoiYnVja2V0LW5hbWUifSx7ImtleSI6Im9iamVjdC1uYW1lIn0seyJ4LWdvb2ctZGF0ZSI6IjIwMjAwMzEyVDExNDcxNloifSx7IngtZ29vZy1jcmVkZW50aWFsIjoidGVzdEBtYWlsLmNvbS8yMDIwMDMxMi9hdXRvL3N0b3JhZ2UvZ29vZzRfcmVxdWVzdCJ9LHsieC1nb29nLWFsZ29yaXRobSI6IkdPT0c0LVJTQS1TSEEyNTYifV0sImV4cGlyYXRpb24iOiIyMDIwLTAzLTI2VDAwOjAwOjEwWiJ9"
+        EXPECTED_POLICY = "eyJjb25kaXRpb25zIjpbeyJidWNrZXQiOiJidWNrZXQtbmFtZSJ9LHsiYWNsIjoicHJpdmF0ZSJ9LFsic3RhcnRzLXdpdGgiLCIkQ29udGVudC1UeXBlIiwidGV4dC9wbGFpbiJdLHsiYnVja2V0IjoiYnVja2V0LW5hbWUifSx7ImtleSI6Im9iamVjdC1uYW1lIn0seyJ4LWdvb2ctZGF0ZSI6IjIwMjAwMzEyVDExNDcxNloifSx7IngtZ29vZy1jcmVkZW50aWFsIjoidGVzdEBtYWlsLmNvbS8yMDIwMDMxMi9hdXRvL3N0b3JhZ2UvZ29vZzRfcmVxdWVzdCJ9LHsieC1nb29nLWFsZ29yaXRobSI6IkdPT0c0LVJTQS1TSEEyNTYifV0sImV4cGlyYXRpb24iOiIyMDIwLTAzLTI2VDAwOjAwOjEwWiJ9"
 
         client = self._make_one(project="PROJECT")
 
@@ -1644,7 +1644,7 @@ def test_get_signed_policy_v4_without_credentials(self):
         BUCKET_NAME = "bucket-name"
         BLOB_NAME = "object-name"
         EXPECTED_SIGN = "5369676e61747572655f6279746573"
-        EXPECTED_POLICY = b"eyJjb25kaXRpb25zIjpbeyJidWNrZXQiOiJidWNrZXQtbmFtZSJ9LHsiYWNsIjoicHJpdmF0ZSJ9LFsic3RhcnRzLXdpdGgiLCIkQ29udGVudC1UeXBlIiwidGV4dC9wbGFpbiJdLHsiYnVja2V0IjoiYnVja2V0LW5hbWUifSx7ImtleSI6Im9iamVjdC1uYW1lIn0seyJ4LWdvb2ctZGF0ZSI6IjIwMjAwMzEyVDExNDcxNloifSx7IngtZ29vZy1jcmVkZW50aWFsIjoidGVzdEBtYWlsLmNvbS8yMDIwMDMxMi9hdXRvL3N0b3JhZ2UvZ29vZzRfcmVxdWVzdCJ9LHsieC1nb29nLWFsZ29yaXRobSI6IkdPT0c0LVJTQS1TSEEyNTYifV0sImV4cGlyYXRpb24iOiIyMDIwLTAzLTI2VDAwOjAwOjEwWiJ9"
+        EXPECTED_POLICY = "eyJjb25kaXRpb25zIjpbeyJidWNrZXQiOiJidWNrZXQtbmFtZSJ9LHsiYWNsIjoicHJpdmF0ZSJ9LFsic3RhcnRzLXdpdGgiLCIkQ29udGVudC1UeXBlIiwidGV4dC9wbGFpbiJdLHsiYnVja2V0IjoiYnVja2V0LW5hbWUifSx7ImtleSI6Im9iamVjdC1uYW1lIn0seyJ4LWdvb2ctZGF0ZSI6IjIwMjAwMzEyVDExNDcxNloifSx7IngtZ29vZy1jcmVkZW50aWFsIjoidGVzdEBtYWlsLmNvbS8yMDIwMDMxMi9hdXRvL3N0b3JhZ2UvZ29vZzRfcmVxdWVzdCJ9LHsieC1nb29nLWFsZ29yaXRobSI6IkdPT0c0LVJTQS1TSEEyNTYifV0sImV4cGlyYXRpb24iOiIyMDIwLTAzLTI2VDAwOjAwOjEwWiJ9"
 
         client = self._make_one(
             project="PROJECT", credentials=_create_signing_credentials()
@@ -1684,7 +1684,7 @@ def test_get_signed_policy_v4_with_fields(self):
         BLOB_NAME = "object-name"
         FIELD1_VALUE = "Value1"
         EXPECTED_SIGN = "5369676e61747572655f6279746573"
-        EXPECTED_POLICY = b"eyJjb25kaXRpb25zIjpbeyJidWNrZXQiOiJidWNrZXQtbmFtZSJ9LHsiYWNsIjoicHJpdmF0ZSJ9LFsic3RhcnRzLXdpdGgiLCIkQ29udGVudC1UeXBlIiwidGV4dC9wbGFpbiJdLHsiZmllbGQxIjoiVmFsdWUxIn0seyJidWNrZXQiOiJidWNrZXQtbmFtZSJ9LHsia2V5Ijoib2JqZWN0LW5hbWUifSx7IngtZ29vZy1kYXRlIjoiMjAyMDAzMTJUMTE0NzE2WiJ9LHsieC1nb29nLWNyZWRlbnRpYWwiOiJ0ZXN0QG1haWwuY29tLzIwMjAwMzEyL2F1dG8vc3RvcmFnZS9nb29nNF9yZXF1ZXN0In0seyJ4LWdvb2ctYWxnb3JpdGhtIjoiR09PRzQtUlNBLVNIQTI1NiJ9XSwiZXhwaXJhdGlvbiI6IjIwMjAtMDMtMjZUMDA6MDA6MTBaIn0="
+        EXPECTED_POLICY = "eyJjb25kaXRpb25zIjpbeyJidWNrZXQiOiJidWNrZXQtbmFtZSJ9LHsiYWNsIjoicHJpdmF0ZSJ9LFsic3RhcnRzLXdpdGgiLCIkQ29udGVudC1UeXBlIiwidGV4dC9wbGFpbiJdLHsiZmllbGQxIjoiVmFsdWUxIn0seyJidWNrZXQiOiJidWNrZXQtbmFtZSJ9LHsia2V5Ijoib2JqZWN0LW5hbWUifSx7IngtZ29vZy1kYXRlIjoiMjAyMDAzMTJUMTE0NzE2WiJ9LHsieC1nb29nLWNyZWRlbnRpYWwiOiJ0ZXN0QG1haWwuY29tLzIwMjAwMzEyL2F1dG8vc3RvcmFnZS9nb29nNF9yZXF1ZXN0In0seyJ4LWdvb2ctYWxnb3JpdGhtIjoiR09PRzQtUlNBLVNIQTI1NiJ9XSwiZXhwaXJhdGlvbiI6IjIwMjAtMDMtMjZUMDA6MDA6MTBaIn0="
 
         client = self._make_one(project="PROJECT")
 
@@ -1774,7 +1774,7 @@ def test_get_signed_policy_v4_bucket_bound_hostname_with_scheme(self):
 
     def test_get_signed_policy_v4_no_expiration(self):
         BUCKET_NAME = "bucket-name"
-        EXPECTED_POLICY = b"eyJjb25kaXRpb25zIjpbeyJidWNrZXQiOiJidWNrZXQtbmFtZSJ9LHsia2V5Ijoib2JqZWN0LW5hbWUifSx7IngtZ29vZy1kYXRlIjoiMjAyMDAzMTJUMTE0NzE2WiJ9LHsieC1nb29nLWNyZWRlbnRpYWwiOiJ0ZXN0QG1haWwuY29tLzIwMjAwMzEyL2F1dG8vc3RvcmFnZS9nb29nNF9yZXF1ZXN0In0seyJ4LWdvb2ctYWxnb3JpdGhtIjoiR09PRzQtUlNBLVNIQTI1NiJ9XSwiZXhwaXJhdGlvbiI6IjIwMjAtMDMtMjZUMDA6MDA6MTBaIn0="
+        EXPECTED_POLICY = "eyJjb25kaXRpb25zIjpbeyJidWNrZXQiOiJidWNrZXQtbmFtZSJ9LHsia2V5Ijoib2JqZWN0LW5hbWUifSx7IngtZ29vZy1kYXRlIjoiMjAyMDAzMTJUMTE0NzE2WiJ9LHsieC1nb29nLWNyZWRlbnRpYWwiOiJ0ZXN0QG1haWwuY29tLzIwMjAwMzEyL2F1dG8vc3RvcmFnZS9nb29nNF9yZXF1ZXN0In0seyJ4LWdvb2ctYWxnb3JpdGhtIjoiR09PRzQtUlNBLVNIQTI1NiJ9XSwiZXhwaXJhdGlvbiI6IjIwMjAtMDMtMjZUMDA6MDA6MTBaIn0="
 
         client = self._make_one(project="PROJECT")
 
@@ -1798,7 +1798,7 @@ def test_get_signed_policy_v4_with_access_token(self):
         BUCKET_NAME = "bucket-name"
         BLOB_NAME = "object-name"
         EXPECTED_SIGN = "0c4003044105"
-        EXPECTED_POLICY = b"eyJjb25kaXRpb25zIjpbeyJidWNrZXQiOiJidWNrZXQtbmFtZSJ9LHsiYWNsIjoicHJpdmF0ZSJ9LFsic3RhcnRzLXdpdGgiLCIkQ29udGVudC1UeXBlIiwidGV4dC9wbGFpbiJdLHsiYnVja2V0IjoiYnVja2V0LW5hbWUifSx7ImtleSI6Im9iamVjdC1uYW1lIn0seyJ4LWdvb2ctZGF0ZSI6IjIwMjAwMzEyVDExNDcxNloifSx7IngtZ29vZy1jcmVkZW50aWFsIjoidGVzdEBtYWlsLmNvbS8yMDIwMDMxMi9hdXRvL3N0b3JhZ2UvZ29vZzRfcmVxdWVzdCJ9LHsieC1nb29nLWFsZ29yaXRobSI6IkdPT0c0LVJTQS1TSEEyNTYifV0sImV4cGlyYXRpb24iOiIyMDIwLTAzLTI2VDAwOjAwOjEwWiJ9"
+        EXPECTED_POLICY = "eyJjb25kaXRpb25zIjpbeyJidWNrZXQiOiJidWNrZXQtbmFtZSJ9LHsiYWNsIjoicHJpdmF0ZSJ9LFsic3RhcnRzLXdpdGgiLCIkQ29udGVudC1UeXBlIiwidGV4dC9wbGFpbiJdLHsiYnVja2V0IjoiYnVja2V0LW5hbWUifSx7ImtleSI6Im9iamVjdC1uYW1lIn0seyJ4LWdvb2ctZGF0ZSI6IjIwMjAwMzEyVDExNDcxNloifSx7IngtZ29vZy1jcmVkZW50aWFsIjoidGVzdEBtYWlsLmNvbS8yMDIwMDMxMi9hdXRvL3N0b3JhZ2UvZ29vZzRfcmVxdWVzdCJ9LHsieC1nb29nLWFsZ29yaXRobSI6IkdPT0c0LVJTQS1TSEEyNTYifV0sImV4cGlyYXRpb24iOiIyMDIwLTAzLTI2VDAwOjAwOjEwWiJ9"
 
         client = self._make_one(project="PROJECT")