diff --git a/db/src/main/java/net/zhira/varioutil/sql/AbstractProvider.java b/db/src/main/java/net/zhira/varioutil/sql/AbstractProvider.java
index 156e72e..81d1d2d 100644
--- a/db/src/main/java/net/zhira/varioutil/sql/AbstractProvider.java
+++ b/db/src/main/java/net/zhira/varioutil/sql/AbstractProvider.java
@@ -23,7 +23,7 @@ abstract class AbstractProvider implements ConnectionProvider {
     @Override
     public boolean isClosed() {
         try {
-            return connection.isClosed();
+            return connection == null || connection.isClosed();
         } catch (SQLException e) {
             throw new SqlException(e);
         }