diff --git a/Dockerfile b/Dockerfile
index f3bc03e..6d46012 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -18,6 +18,8 @@ VOLUME [ "/var/lib/nginx/pypi" ]
 EXPOSE 80
 
 ENV TZ=Pacific/Auckland 
+# Transport scheme default is https
+ENV TRANSPORT_SCHEME=https
 
 ENTRYPOINT [ "/docker-entrypoint.sh" ]
 
diff --git a/conf/nginx.conf b/conf/nginx.conf
index 0fcf585..7157c9a 100644
--- a/conf/nginx.conf
+++ b/conf/nginx.conf
@@ -81,8 +81,8 @@ http {
 
     location / {
       # Replace any reference to actual pypi w/ caching proxy
-      sub_filter 'https://pypi.org' $scheme://$host;
-      sub_filter 'https://files.pythonhosted.org' $scheme://%%PYPI_FILES_HOSTNAME%%;
+      sub_filter 'https://pypi.org' %%TRANSPORT_SCHEME%%://$host;
+      sub_filter 'https://files.pythonhosted.org' %%TRANSPORT_SCHEME%%://%%PYPI_FILES_HOSTNAME%%;
       sub_filter_once off;
       sub_filter_types '*';
       proxy_pass https://pypi;
@@ -90,8 +90,8 @@ http {
     }
 
     location ^~ /simple {
-      sub_filter 'https://pypi.org' $scheme://$host;
-      sub_filter 'https://files.pythonhosted.org' $scheme://%%PYPI_FILES_HOSTNAME%%;
+      sub_filter 'https://pypi.org' %%TRANSPORT_SCHEME%%://$host;
+      sub_filter 'https://files.pythonhosted.org' %%TRANSPORT_SCHEME%%://%%PYPI_FILES_HOSTNAME%%;
       sub_filter_types '*';
       sub_filter_once off;
       # Make sure URI ends with /
@@ -128,7 +128,7 @@ http {
 
     location / {
       # Replace any reference to actual pypi w/ caching proxy
-      sub_filter 'https://files.pythonhosted.org' $scheme://%%PYPI_FILES_HOSTNAME%%;
+      sub_filter 'https://files.pythonhosted.org' %%TRANSPORT_SCHEME%%://%%PYPI_FILES_HOSTNAME%%;
       sub_filter_once off;
       sub_filter_types '*';
       proxy_pass https://pypi-files;