diff --git a/functional_tests/base.py b/functional_tests/base.py
index c4d837e23f452cca412afa5b582e21f254cc7380..dffee6eb6aedccbea87730605e5020b77f88b3a8 100644
--- a/functional_tests/base.py
+++ b/functional_tests/base.py
@@ -89,7 +89,7 @@ def run_interactive_command(prompt_answers, command, *args):
     # stdout/stderr.
     output_stream = io.StringIO()
     send_stream = io.StringIO()
-    process = pexpect.spawnu(command, [*args], timeout=2)
+    process = pexpect.spawnu(command, list(args), timeout=2)
     process.logfile_read = output_stream
     process.logfile_send = send_stream
 
diff --git a/gimmecert/storage.py b/gimmecert/storage.py
index 9dc268315a297a8ce7c8b1dd342030927cc1044b..2475ec65d8541a77db5e1d6442628a982aeabea6 100644
--- a/gimmecert/storage.py
+++ b/gimmecert/storage.py
@@ -103,11 +103,11 @@ def write_certificate_chain(certificate_chain, path):
     :type path: str
     """
 
-    chain_pem = b"\n".join(
+    chain_pem = "\n".join(
         [gimmecert.utils.certificate_to_pem(certificate) for certificate in certificate_chain]
     )
 
-    with open(path, 'wb') as certificate_chain_file:
+    with open(path, 'w') as certificate_chain_file:
         certificate_chain_file.write(chain_pem)
 
 
diff --git a/gimmecert/utils.py b/gimmecert/utils.py
index 1dabbc3873b59e89b4a2fe78143f68b070346ac3..8ae4d48c7ea16bbeb1e4e0a70827997e0190cb7d 100644
--- a/gimmecert/utils.py
+++ b/gimmecert/utils.py
@@ -38,12 +38,12 @@ def certificate_to_pem(certificate):
     :type certificate: cryptography.x509.Certificate
 
     :returns: Certificate in OpenSSL-style PEM format.
-    :rtype: bytes
+    :rtype: str
     """
 
     certificate_pem = certificate.public_bytes(encoding=cryptography.hazmat.primitives.serialization.Encoding.PEM)
 
-    return certificate_pem
+    return certificate_pem.decode()
 
 
 def dn_to_str(dn):
diff --git a/tests/test_cli.py b/tests/test_cli.py
index a549e2352d47052fba327fe4f8f41eb28c0fd5a2..3bd3edca2fce6fb107e93fb4c0fef93bc089d3de 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -211,7 +211,7 @@ def test_setup_subcommand_parser_registered(setup_subcommand_parser):
 # command from CLI. See test documentation for more details.
 VALID_CLI_INVOCATIONS = [
     # help, no options
-    ("gimmecert.cli.help", ["gimmecert", "help"]),
+    ("gimmecert.cli.help_", ["gimmecert", "help"]),
 
     # init, no options
     ("gimmecert.cli.init", ["gimmecert", "init"]),
diff --git a/tests/test_storage.py b/tests/test_storage.py
index 6c0ede6eac169e614a1253b2236ed7a0964ad84b..23cf3de5394cd04d09b7efdb5a397cc8e30fdc14 100644
--- a/tests/test_storage.py
+++ b/tests/test_storage.py
@@ -84,8 +84,8 @@ def test_write_certificate_chain(tmpdir):
     level1_pem, level2_pem, level3_pem = [gimmecert.utils.certificate_to_pem(certificate) for certificate in certificate_chain]
 
     gimmecert.storage.write_certificate_chain(certificate_chain, output_file.strpath)
-    content = output_file.read(mode='rb')
-    expected_content = b"%s\n%s\n%s" % (level1_pem, level2_pem, level3_pem)
+    content = output_file.read(mode='r')
+    expected_content = "%s\n%s\n%s" % (level1_pem, level2_pem, level3_pem)
 
     assert content == expected_content
 
diff --git a/tests/test_utils.py b/tests/test_utils.py
index d5d13ebbe5a8a2dca9eba791b7616a1542229b20..1fc1f0d4b4d7cebb00291cc87a7930e13a46b98b 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -39,8 +39,9 @@ def test_certificate_to_pem_returns_valid_pem():
 
     certificate_pem = gimmecert.utils.certificate_to_pem(certificate)
 
-    assert isinstance(certificate_pem, bytes)
-    certificate_from_pem = cryptography.x509.load_pem_x509_certificate(certificate_pem, cryptography.hazmat.backends.default_backend())  # Should not throw
+    assert isinstance(certificate_pem, str)
+    certificate_from_pem = cryptography.x509.load_pem_x509_certificate(bytes(certificate_pem, encoding='UTF-8'),
+                                                                       cryptography.hazmat.backends.default_backend())  # Should not throw
     assert certificate_from_pem.subject == certificate.subject
     assert certificate_from_pem.issuer == certificate.issuer