diff --git a/src/Connection.php b/src/Connection.php
index 5567cf8..da4e052 100644
--- a/src/Connection.php
+++ b/src/Connection.php
@@ -384,12 +384,12 @@ public function yieldPairs(Select|string $stmt, ?array $values = null): Generato
     /**
      * Prepare and execute the given statement
      *
-     * @param Delete|Insert|Select|Update|string $stmt   The SQL statement to prepare and execute
-     * @param string|array                       $values Values to bind to the statement, if any
+     * @param Delete|Insert|Select|Update|string $stmt The SQL statement to prepare and execute
+     * @param string|array|null $values Values to bind to the statement, if any
      *
      * @return PDOStatement
      */
-    public function prepexec($stmt, $values = null)
+    public function prepexec(Delete|Insert|Select|Update|string $stmt, string|array|null $values = null): PDOStatement
     {
         if ($values !== null && ! is_array($values)) {
             $values = [$values];
diff --git a/src/Test/TestConnection.php b/src/Test/TestConnection.php
index 1e149b8..30e7cba 100644
--- a/src/Test/TestConnection.php
+++ b/src/Test/TestConnection.php
@@ -3,6 +3,11 @@
 namespace ipl\Sql\Test;
 
 use ipl\Sql\Connection;
+use ipl\Sql\Delete;
+use ipl\Sql\Insert;
+use ipl\Sql\Select;
+use ipl\Sql\Update;
+use PDOStatement;
 
 /**
  * Config-less test connection
@@ -34,7 +39,7 @@ public function rollbackTransaction(): bool
         throw new \LogicException('Transactions are not supported by the test connection');
     }
 
-    public function prepexec($stmt, $values = null)
+    public function prepexec(Delete|Insert|Select|Update|string $stmt, string|array|null $values = null): PDOStatement
     {
         if (PHP_MAJOR_VERSION >= 8) {
             return new class extends \PDOStatement {