diff --git a/src/pumpfun_cli/commands/config.py b/src/pumpfun_cli/commands/config.py
index 4723fc1..6403803 100644
--- a/src/pumpfun_cli/commands/config.py
+++ b/src/pumpfun_cli/commands/config.py
@@ -18,9 +18,17 @@ def _config_callback(ctx: typer.Context):
         raise SystemExit(0)
 
 
+KNOWN_KEYS = {"rpc", "keyfile", "priority_fee", "compute_units"}
+
+
 @app.command("set")
 def config_set(ctx: typer.Context, key: str, value: str):
     """Set a config value."""
+    if key not in KNOWN_KEYS:
+        error(
+            f"Unknown config key: {key}",
+            hint=f"Valid keys: {', '.join(sorted(KNOWN_KEYS))}",
+        )
     save_config_value(key, value)
     json_mode = ctx.obj.json_mode if ctx.obj else False
     if not render({"key": key, "value": value, "status": "saved"}, json_mode):
diff --git a/tests/test_commands/test_config_cmd.py b/tests/test_commands/test_config_cmd.py
index f2a3b41..fbb7bb4 100644
--- a/tests/test_commands/test_config_cmd.py
+++ b/tests/test_commands/test_config_cmd.py
@@ -80,3 +80,12 @@ def test_config_get_json_trailing(tmp_path, monkeypatch):
     assert result.exit_code == 0
     data = json.loads(result.output)
     assert data == {"key": "rpc", "value": "https://example.com"}
+
+
+def test_config_set_unknown_key(tmp_path, monkeypatch):
+    """config set rejects unknown config keys."""
+    monkeypatch.setenv("XDG_CONFIG_HOME", str(tmp_path))
+    result = runner.invoke(app, ["config", "set", "rpcc", "https://example.com"])
+    assert result.exit_code != 0
+    assert "unknown config key" in result.output.lower()
+    assert "valid keys" in result.output.lower()