--- ../libqmi-1.16.0/src/libqmi-glib/qmi-device.c	2016-11-04 10:51:52.870085915 +0100
+++ src/libqmi-glib/qmi-device.c	2016-11-03 15:18:04.077950054 +0100
@@ -244,14 +244,16 @@
     GError *error = NULL;
 
     tr = device_release_transaction (ctx->self, ctx->key);
-    tr->timeout_source = NULL;
+    if (tr) {
+        tr->timeout_source = NULL;
 
-    /* Complete transaction with a timeout error */
-    error = g_error_new (QMI_CORE_ERROR,
-                         QMI_CORE_ERROR_TIMEOUT,
-                         "Transaction timed out");
-    transaction_complete_and_free (tr, NULL, error);
-    g_error_free (error);
+        /* Complete transaction with a timeout error */
+        error = g_error_new (QMI_CORE_ERROR,
+                             QMI_CORE_ERROR_TIMEOUT,
+                             "Transaction timed out");
+        transaction_complete_and_free (tr, NULL, error);
+        g_error_free (error);
+    }
 
     return FALSE;
 }
@@ -264,14 +266,16 @@
     GError *error = NULL;
 
     tr = device_release_transaction (ctx->self, ctx->key);
-    tr->cancellable_id = 0;
+    if (tr) {
+        tr->cancellable_id = 0;
 
-    /* Complete transaction with an abort error */
-    error = g_error_new (QMI_PROTOCOL_ERROR,
-                         QMI_PROTOCOL_ERROR_ABORTED,
-                         "Transaction aborted");
-    transaction_complete_and_free (tr, NULL, error);
-    g_error_free (error);
+        /* Complete transaction with an abort error */
+        error = g_error_new (QMI_PROTOCOL_ERROR,
+                             QMI_PROTOCOL_ERROR_ABORTED,
+                             "Transaction aborted");
+        transaction_complete_and_free (tr, NULL, error);
+        g_error_free (error);
+    }
 }
 
 static gboolean