diff --git a/CHANGES b/CHANGES
index cf7ebfc03ab..ffd8cfba1cb 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,6 +1,10 @@
                                                          -*- coding: utf-8 -*-
 Changes with Apache 2.4.63
 
+  *) mod_rewrite: Don't require [UNC] flag to preserve a leading //
+     added by applying the perdir prefix to the substitution.
+     [Ruediger Pluem, Eric Covener]
+
   *) Windows: Restore the ability to "Include" configuration files on UNC
      paths. PR69313 [Eric Covener]
 
diff --git a/modules/mappers/mod_rewrite.c b/modules/mappers/mod_rewrite.c
index 24e21c6f4dc..ef3e52fb794 100644
--- a/modules/mappers/mod_rewrite.c
+++ b/modules/mappers/mod_rewrite.c
@@ -4322,6 +4322,7 @@ static rule_return_type apply_rewrite_rule(rewriterule_entry *p,
     char *newuri = NULL;
     request_rec *r = ctx->r;
     int is_proxyreq = 0;
+    int prefix_added = 0;
 
     ctx->uri = r->filename;
 
@@ -4483,6 +4484,7 @@ static rule_return_type apply_rewrite_rule(rewriterule_entry *p,
                        newuri, ctx->perdir, newuri);
 
             newuri = apr_pstrcat(r->pool, ctx->perdir, newuri, NULL);
+            prefix_added = 1;
         }
         else if (!(p->flags & (RULEFLAG_PROXY | RULEFLAG_FORCEREDIRECT))) {
             /* Not an absolute URI-path and the scheme (if any) is unknown,
@@ -4496,6 +4498,7 @@ static rule_return_type apply_rewrite_rule(rewriterule_entry *p,
                        newuri, newuri);
 
             newuri = apr_pstrcat(r->pool, "/", newuri, NULL);
+            prefix_added = 1;
         }
     }
 
@@ -4576,7 +4579,7 @@ static rule_return_type apply_rewrite_rule(rewriterule_entry *p,
         return RULE_RC_MATCH;
     }
 
-    if (!(p->flags & RULEFLAG_UNC)) {
+    if (!((p->flags & RULEFLAG_UNC) || prefix_added)) {
         /* merge leading slashes, unless they were literals in the sub */
         if (!AP_IS_SLASH(p->output[0]) || !AP_IS_SLASH(p->output[1])) {
             while (AP_IS_SLASH(r->filename[0]) &&