Index: modules/proxy/mod_proxy.c
===================================================================
--- modules/proxy/mod_proxy.c	(revision 1520080)
+++ modules/proxy/mod_proxy.c	(working copy)
@@ -1424,6 +1424,9 @@
     int use_regex = is_regex;
     unsigned int flags = 0;
     const char *err;
+    int interpolated_scheme = FALSE;
+    char *scheme = NULL;
+    const char *c;
 
     err = ap_check_cmd_context(cmd, NOT_IN_DIRECTORY|NOT_IN_FILES);
     if (err) {
@@ -1536,10 +1539,27 @@
         proxy_worker *worker = ap_proxy_get_worker(cmd->temp_pool, NULL, conf, r);
         int reuse = 0;
         if (!worker) {
+            if (flags & PROXYPASS_INTERPOLATE) {
+                if (!strncmp(r, "${", 2)) {
+                    c = ap_strchr_c(r, ':');
+                    if (c != NULL && *(c - 1) == '}') {
+                        scheme = apr_pstrndup(cmd->temp_pool, r, c - r);
+                        r = apr_pstrcat(cmd->temp_pool, "http", c, NULL);
+                        interpolated_scheme = TRUE;
+                    }
+                }
+            }
+
             const char *err = ap_proxy_define_worker(cmd->pool, &worker, NULL, conf, r, 0);
             if (err)
                 return apr_pstrcat(cmd->temp_pool, "ProxyPass ", err, NULL);
 
+            if (interpolated_scheme) {
+                if (PROXY_STRNCPY(worker->s->scheme, scheme) != APR_SUCCESS) {
+                    return apr_pstrcat(cmd->temp_pool, "worker scheme (%s) too long", scheme);
+                }
+            }
+
             PROXY_COPY_CONF_PARAMS(worker, conf);
         } else {
             reuse = 1;