diff --git a/oarepo_c4gh/key/gpg_agent.py b/oarepo_c4gh/key/gpg_agent.py
index 185c4a1..ef7b949 100644
--- a/oarepo_c4gh/key/gpg_agent.py
+++ b/oarepo_c4gh/key/gpg_agent.py
@@ -147,24 +147,22 @@ def ensure_public_key(self):
                 key_dgram = client.recv(4096)
                 key_line, key_rest = line_from_dgram(key_dgram)
                 key_struct = parse_binary_sexp(key_line[2:])
-                if key_struct is None:
-                    continue
-                if len(key_struct) < 2:
-                    continue
-                if key_struct[0] != b"public-key":
-                    continue
-                if len(key_struct[1]) < 1:
-                    continue
-                if key_struct[1][0] != b"ecc":
+                if (
+                    (key_struct is None)
+                    or (len(key_struct) < 2)
+                    or (key_struct[0] != b"public-key")
+                    or (len(key_struct[1])) < 1
+                    or (key_struct[1][0] != b"ecc")
+                ):
                     continue
                 curve_struct = next(
                     v for v in key_struct[1][1:] if v[0] == b"curve"
                 )
-                if curve_struct is None:
-                    continue
-                if len(curve_struct) < 2:
-                    continue
-                if curve_struct[1] != b"Curve25519":
+                if (
+                    (curve_struct is None)
+                    or (len(curve_struct) < 2)
+                    or (curve_struct[1] != b"Curve25519")
+                ):
                     continue
                 q_struct = next(v for v in key_struct[1][1:] if v[0] == b"q")
                 if q_struct is None:
diff --git a/tests/test_key_gpg_agent.py b/tests/test_key_gpg_agent.py
index 3a32d5f..9ce5716 100644
--- a/tests/test_key_gpg_agent.py
+++ b/tests/test_key_gpg_agent.py
@@ -6,6 +6,8 @@
     compute_run_gnupg_base,
     expect_assuan_OK,
     parse_binary_sexp,
+    encode_assuan_buffer,
+    decode_assuan_buffer,
 )
 from oarepo_c4gh.exceptions import Crypt4GHKeyException
 import socket
@@ -30,6 +32,8 @@ def test_assuan_expect(self):
         self.assertRaises(Crypt4GHKeyException, lambda: expect_assuan_OK(r))
         w.send(b"OK\nnoise")
         self.assertRaises(Crypt4GHKeyException, lambda: expect_assuan_OK(r))
+        r.close()
+        w.close()
 
     def test_assuan_binary_sexps(self):
         assert (
@@ -42,6 +46,25 @@ def test_assuan_binary_sexps(self):
             parse_binary_sexp(b":") is None
         ), "Error handling malformed S-Expression 2"
 
+    def test_assuan_binary_encoding(self):
+        line = b"25%\r\n"
+        eline = encode_assuan_buffer(line)
+        assert eline == b"25%25%0D%0A", "Assuan encoding mismatch"
+        reline = decode_assuan_buffer(eline)
+        assert reline == line, "Assuan encoding round-trip mismatch"
+
+    def test_connection_error(self):
+        key = GPGAgentKey(socket_path="/dev/null")
+        self.assertRaises(Crypt4GHKeyException, lambda: key.public_key)
+
+    def test_empty_keygrips(self):
+        tempdir = tempfile.TemporaryDirectory()
+        homedir = tempdir.name
+        os.system(f"gpg-agent --homedir {homedir} --daemon")
+        key = GPGAgentKey(home_dir=homedir)
+        self.assertRaises(Crypt4GHKeyException, lambda: key.public_key)
+        tempdir.cleanup()
+
     def test_everything(self):
         tempdir = tempfile.TemporaryDirectory()
         homedir = tempdir.name
@@ -51,6 +74,7 @@ def test_everything(self):
         os.system(f"gpg-agent --homedir {homedir} --daemon")
         key = GPGAgentKey(home_dir=homedir)
         key.public_key
+        tempdir.cleanup()
 
 
 if __name__ == "__main__":