diff --git a/viewer/serializers.py b/viewer/serializers.py
index d37d5ca2..19fd2930 100644
--- a/viewer/serializers.py
+++ b/viewer/serializers.py
@@ -53,20 +53,27 @@ def get_template_protein(self, obj):
     def get_zip_archive(self, obj):
         request = self.context["request"]
         # This is to map links to HTTPS to avoid Mixed Content warnings from Chrome browsers
-        # SECURE_PROXY_SSL_HEADER is referenced because it is used in redirecting URLs - if it is changed
-        # it make affect this code.
-        # Using relative links will probably also work, but This workaround allows both the 'download structures'
-        # button and the DRF API call to work.
+        # SECURE_PROXY_SSL_HEADER is referenced because it is used in redirecting URLs - if
+        # it is changed it may affect this code.
+        # Using relative links will probably also work, but This workaround allows both the
+        # 'download structures' button and the DRF API call to work.
+        # The if-check is because the filefield in target has null=True.
         # Note that this link will not work on local
-        https_host = settings.SECURE_PROXY_SSL_HEADER[1]+'://'+request.get_host()
-        return urljoin(https_host, obj.zip_archive.url)
+        https_host = settings.SECURE_PROXY_SSL_HEADER[1] + '://' + request.get_host()
+        if hasattr(obj, 'zip_archive') and obj.zip_archive.name:
+            return urljoin(https_host, obj.zip_archive.url)
+        else:
+            return
 
     def get_metadata(self, obj):
         request = self.context["request"]
         # This is to map links to HTTPS to avoid Mixed Content warnings from Chrome browsers
-        # Note that this link will not work on local - see above.
-        https_host = settings.SECURE_PROXY_SSL_HEADER[1]+'://'+request.get_host()
-        return urljoin(https_host, obj.metadata.url)
+        # See above for details.
+        https_host = settings.SECURE_PROXY_SSL_HEADER[1] + '://' + request.get_host()
+        if hasattr(obj, 'metadata') and obj.metadata.name:
+            return urljoin(https_host, obj.metadata.url)
+        else:
+            return
 
     class Meta:
         model = Target
@@ -458,4 +465,4 @@ def get_text_scores(self, obj):
     #     desc_dict = {}
     #     for desc in descriptions:
     #         desc_dict[desc.name] = desc.description
-    #     return desc_dict
\ No newline at end of file
+    #     return desc_dict