diff --git a/bebop/navigation.py b/bebop/navigation.py
index dcaa8c3..d4de50c 100644
--- a/bebop/navigation.py
+++ b/bebop/navigation.py
@@ -176,3 +176,16 @@ def get_root_url(url: str) -> str:
     parts["path"] = "/"
     clear_post_path(parts)
     return unparse_url(parts)
+
+
+def parse_host_and_port(host: str, default_port: int):
+    """Return the host and port from a "host:port" string."""
+    if ":" in host:
+        host, port = host.split(":", maxsplit=1)
+        try:
+            port = int(port)
+        except ValueError:
+            return None
+    else:
+        port = default_port
+    return host, port
diff --git a/bebop/protocol.py b/bebop/protocol.py
index 20c14d3..42f860a 100644
--- a/bebop/protocol.py
+++ b/bebop/protocol.py
@@ -9,6 +9,7 @@ from enum import IntEnum
 from typing import Optional
 
 from bebop.mime import DEFAULT_MIME_TYPE, MimeType
+from bebop.navigation import parse_host_and_port
 from bebop.tofu import CertStatus, validate_cert
 
 
@@ -127,16 +128,13 @@ class Request:
         if not url_parts:
             self.state = Request.STATE_INVALID_URL
             return False
-        hostname = url_parts.groupdict()["host"]
-        if ":" in hostname:
-            hostname, port = hostname.split(":", maxsplit=1)
-            try:
-                port = int(port)
-            except ValueError:
-                self.state = Request.STATE_INVALID_URL
-                return False
-        else:
-            port = 1965
+
+        host = url_parts.groupdict()["host"]
+        host_and_port = parse_host_and_port(host, 1965)
+        if host_and_port is None:
+            self.state = Request.STATE_INVALID_URL
+            return False
+        hostname, port = host_and_port
         self.hostname = hostname
 
         # Prepare the Gemini request.