diff --git a/src/lib/bag.cpp b/src/lib/bag.cpp
index c860457..b11373d 100644
--- a/src/lib/bag.cpp
+++ b/src/lib/bag.cpp
@@ -152,7 +152,9 @@ bool Bag::store( string basedir ) {
 		bagit_txt_file.close();
 	} else {
 		Bag::log << "file " << bagit_txt_path << "could not be open for writing" << endl;
+		return false;
 	}
+	return true;
 }
 
 
@@ -243,16 +245,18 @@ bool Bag::validate() {
     if (this->bagmetadata_p->has_oxum()) {
       // check oxum of payload
       Checksum c;
-      list<string> files = this->payload_p->get_all_absolute_paths();
-      oxum_t expected_oxum = this->bagmetadata_p->get_oxum();
-      oxum_t calculated_oxum = c.oxum_of_filelist( files );
-      if (expected_oxum.octetcount != calculated_oxum.octetcount) {
-        this->log << "Bagit payload oxum octectcount=" << to_string(expected_oxum.octetcount) << " expected, but " << to_string(calculated_oxum.octetcount) << " found" << endl;
-        is_valid = false;
-      }
-      if (expected_oxum.streamcount != calculated_oxum.streamcount) {
-        this->log << "Bagit payload oxum streamcount=" << to_string(expected_oxum.streamcount) << " expected, but " << to_string(calculated_oxum.streamcount) << " found" << endl;
-        is_valid = false;
+      if (this->payload_p != nullptr) {
+	      list<string> files = this->payload_p->get_all_absolute_paths();
+	      oxum_t expected_oxum = this->bagmetadata_p->get_oxum();
+	      oxum_t calculated_oxum = c.oxum_of_filelist( files );
+	      if (expected_oxum.octetcount != calculated_oxum.octetcount) {
+		      this->log << "Bagit payload oxum octectcount=" << to_string(expected_oxum.octetcount) << " expected, but " << to_string(calculated_oxum.octetcount) << " found" << endl;
+		      is_valid = false;
+	      }
+	      if (expected_oxum.streamcount != calculated_oxum.streamcount) {
+		      this->log << "Bagit payload oxum streamcount=" << to_string(expected_oxum.streamcount) << " expected, but " << to_string(calculated_oxum.streamcount) << " found" << endl;
+		      is_valid = false;
+	      }
       }
 
     }