diff --git a/src/Internal/PgSqlHandle.php b/src/Internal/PgSqlHandle.php
index 33a64fd..a148067 100644
--- a/src/Internal/PgSqlHandle.php
+++ b/src/Internal/PgSqlHandle.php
@@ -62,6 +62,8 @@ public function __construct(
     ) {
         $this->handle = $handle;
 
+        $this->types = (self::$typeCache[$id] ??= self::fetchTypes($handle));
+
         $handle = &$this->handle;
         $lastUsedAt = &$this->lastUsedAt;
         $deferred = &$this->pendingOperation;
@@ -75,6 +77,11 @@ public function __construct(
             &$handle,
             $onClose,
         ): void {
+            if (!$handle) {
+                EventLoop::disable($watcher);
+                return;
+            }
+
             $lastUsedAt = \time();
 
             \set_error_handler(self::getErrorHandler());
@@ -129,6 +136,11 @@ public function __construct(
             &$handle,
             $onClose,
         ): void {
+            if (!$handle) {
+                EventLoop::disable($watcher);
+                return;
+            }
+
             \set_error_handler(self::getErrorHandler());
 
             try {
@@ -156,8 +168,6 @@ public function __construct(
         EventLoop::disable($await);
 
         parent::__construct($config, $poll, $await, $onClose);
-
-        $this->types = (self::$typeCache[$id] ??= self::fetchTypes($handle));
     }
 
     /**
diff --git a/src/Internal/PqHandle.php b/src/Internal/PqHandle.php
index 0e22976..252b4e4 100644
--- a/src/Internal/PqHandle.php
+++ b/src/Internal/PqHandle.php
@@ -87,7 +87,7 @@ public function __construct(pq\Connection $handle, PostgresConfig $config)
             $onClose,
         ): void {
             try {
-                if (!$handle->flush()) {
+                if (!$handle?->flush()) {
                     return; // Not finished sending data, continue polling for writability.
                 }
             } catch (pq\Exception $exception) {
diff --git a/src/Internal/functions.php b/src/Internal/functions.php
index 7ba2011..f872cf1 100644
--- a/src/Internal/functions.php
+++ b/src/Internal/functions.php
@@ -27,6 +27,7 @@
 
 /**
  * @internal
+ * @psalm-suppress ReferenceConstraintViolation
  *
  * @param string $sql SQL statement with named and unnamed placeholders.
  * @param-out list<int|string> $names Array of parameter positions mapped to names and/or indexed locations.
diff --git a/src/PgSqlConnection.php b/src/PgSqlConnection.php
index c15023b..d451a3c 100644
--- a/src/PgSqlConnection.php
+++ b/src/PgSqlConnection.php
@@ -35,8 +35,19 @@ public static function connect(PostgresConfig $config, ?Cancellation $cancellati
         $hash = \sha1($config->getHost() . $config->getPort() . $config->getUser());
 
         $deferred = new DeferredFuture();
-        /** @psalm-suppress MissingClosureParamType $resource is a resource and cannot be inferred in this context */
-        $callback = static function (string $callbackId, $resource) use (&$poll, &$await, $connection, $config, $deferred, $hash): void {
+
+        /**
+         * @psalm-suppress MissingClosureParamType $resource is a resource and cannot be inferred in this context.
+         * @psalm-suppress UndefinedVariable $poll is defined below.
+         */
+        $callback = static function (string $callbackId, $resource) use (
+            &$poll,
+            &$await,
+            $connection,
+            $config,
+            $deferred,
+            $hash,
+        ): void {
             switch ($result = \pg_connect_poll($connection)) {
                 case \PGSQL_POLLING_READING:
                 case \PGSQL_POLLING_WRITING:
diff --git a/src/PqConnection.php b/src/PqConnection.php
index 23a94c2..3284474 100644
--- a/src/PqConnection.php
+++ b/src/PqConnection.php
@@ -24,7 +24,9 @@ public static function connect(PostgresConfig $config, ?Cancellation $cancellati
         $connection->unbuffered = true;
 
         $deferred = new DeferredFuture();
-        $callback = function () use (&$poll, &$await, $connection, $config, $deferred): void {
+
+        /** @psalm-suppress UndefinedVariable $poll is defined below. */
+        $callback = static function () use (&$poll, &$await, $connection, $config, $deferred): void {
             switch ($result = $connection->poll()) {
                 case pq\Connection::POLLING_READING:
                 case pq\Connection::POLLING_WRITING: