diff --git a/README.md b/README.md
index 1097ba2..bcdc250 100644
--- a/README.md
+++ b/README.md
@@ -149,6 +149,9 @@ key (`host:port:user:pass`, or `host:port` auth-less; the port is normalized so
 differing only by password are distinct slots. `burn` on a proxy not in the pool raises
 `ValueError`; `restore` on a proxy not in the pool logs a warning and no-ops (matching
 `remove`'s contract, as of v0.3.0 — previously it silently did nothing with no signal).
+A **portless** url (`http://user:pass@host`, no `:port`) parses fine via `to_proxy()`,
+but keying it (`canonical_key`/`.key()`/`burn`/`add`/`remove`) raises `ValueError`
+naming the missing port — a proxy needs a port to have a canonical identity.
 
 ### Cooldown
 
@@ -209,6 +212,17 @@ await reset("https://provider/reset-url")    # rotate upstream ip
 
 ## Changelog
 
+### v0.3.2
+
+- **Portless proxy url now fails loud and legible.** `canonical_key`/`.key()`
+  (and therefore `burn`/`add`/`remove`) on a proxy url with no `:port`
+  (`http://user:pass@host`) used to raise a bare `ValueError("invalid literal
+  for int() with base 10: ''")` from `normalize_port('')` — an unrelated `int()`
+  error that broke `burn()`'s documented "raises ValueError naming the key if
+  not in pool" contract. `normalize_port` now raises `ValueError("missing port:
+  ...")` naming the problem instead. `to_proxy()` on a portless url still
+  succeeds (construction tolerates a missing port); only keying it raises.
+
 ### v0.3.1
 
 - **Docs-only de-bloat pass.** Compressed module/internal docstrings and comments,
diff --git a/pyproject.toml b/pyproject.toml
index 1c77481..2a8fb57 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "aioproxies"
-version = "0.3.1"
+version = "0.3.2"
 description = "proxy parsing, formatting, health, and pool management for aiohttp/aioweb, camoufox, and socks5"
 requires-python = ">=3.10"
 dependencies = []
diff --git a/src/aioproxies/proxy.py b/src/aioproxies/proxy.py
index 8b21ec6..7eb3588 100644
--- a/src/aioproxies/proxy.py
+++ b/src/aioproxies/proxy.py
@@ -19,9 +19,12 @@ SCHEME_SOCKS5 = "socks5"
 def normalize_port(port: Union[str, int]) -> str:
     """canonical port string: parsed to int, rendered without zero-padding
 
-    keeps host:080 and host:80 as one canonical key. raises ValueError on a
-    non-integer port rather than silently keying it as-is.
+    keeps host:080 and host:80 as one canonical key. raises ValueError naming the
+    missing port if empty/None (e.g. a portless proxy url), or on a non-integer
+    port, rather than silently keying it as-is.
     """
+    if port is None or port == "":
+        raise ValueError("missing port: proxy url or spec has no port")
     return str(int(port))