diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# hpqtypes-1.13.0.1 (2025-11-27)
+* Fix a bug in `initConnectionState` and `finalizeConnectionState` that could
+  lead to leaking connections.
+
 # hpqtypes-1.13.0.0 (2025-11-26)
 * Drop support for GHC < 9.2.
 * Include time spent executing queries in `ConnectionStats`.
diff --git a/hpqtypes.cabal b/hpqtypes.cabal
--- a/hpqtypes.cabal
+++ b/hpqtypes.cabal
@@ -1,7 +1,7 @@
 cabal-version:       3.0
 build-type:          Simple
 name:                hpqtypes
-version:             1.13.0.0
+version:             1.13.0.1
 synopsis:            Haskell bindings to libpqtypes
 
 description:         Efficient and easy-to-use bindings to (slightly modified)
diff --git a/src/Database/PostgreSQL/PQTypes/Internal/State.hs b/src/Database/PostgreSQL/PQTypes/Internal/State.hs
--- a/src/Database/PostgreSQL/PQTypes/Internal/State.hs
+++ b/src/Database/PostgreSQL/PQTypes/Internal/State.hs
@@ -46,9 +46,13 @@
 -- operation, but if these queries are interrupted with an asynchronous
 -- exception, then a connection is leaked, so they need to be run with
 -- asynchronous exceptions hard masked with uninterruptibleMask.
+--
+-- What is more, these queries themselves can throw an exception if e.g. network
+-- goes bye-bye and PostgreSQL can't be reached, therefore they need exception
+-- handlers themselves so connections don't leak.
 
 initConnectionState
-  :: MonadBase IO m
+  :: (MonadBase IO m, MonadMask m)
   => InternalConnectionSource m cdata
   -> ConnectionAcquisitionMode
   -> m (ConnectionState cdata)
@@ -69,11 +73,14 @@
                 ReadWrite -> "READ WRITE"
             ]
     (conn, cdata) <- takeConnection ics
-    _ <- liftBase . uninterruptibleMask_ $ runQueryIO @SQL conn initSql
+    _ <- uninterruptibleMask_ $ do
+      liftBase (runQueryIO @SQL conn initSql) `catch` \e -> do
+        putConnection ics (conn, cdata) (ExitCaseException e)
+        throwM e
     pure $ Acquired tsIsolationLevel tsPermissions conn cdata
 
 finalizeConnectionState
-  :: (HasCallStack, MonadBase IO m)
+  :: (HasCallStack, MonadBase IO m, MonadMask m)
   => InternalConnectionSource m cdata
   -> ExitCase r
   -> ConnectionState cdata
@@ -84,7 +91,10 @@
     let finalizeSql = case ec of
           ExitCaseSuccess _ -> "COMMIT"
           _ -> "ROLLBACK"
-    _ <- liftBase . uninterruptibleMask_ $ runQueryIO @SQL conn finalizeSql
+    _ <- uninterruptibleMask_ $ do
+      liftBase (runQueryIO @SQL conn finalizeSql) `catch` \e -> do
+        putConnection ics (conn, cdata) (ExitCaseException e)
+        throwM e
     putConnection ics (conn, cdata) ec
   Finalized -> error "finalized connection"
 
@@ -202,7 +212,7 @@
     Finalized -> error "finalized connection"
 
 initConnectionData
-  :: MonadBase IO m
+  :: (MonadBase IO m, MonadMask m)
   => ConnectionSourceM m
   -> ConnectionAcquisitionMode
   -> m (ConnectionData m)