Index: modules/filters/mod_include.c
===================================================================
--- modules/filters/mod_include.c	(revision 736307)
+++ modules/filters/mod_include.c	(working copy)
@@ -3052,6 +3052,17 @@
 {
     include_dir_config *conf;
 
+    /* If we're already on the filter chain, adding a second
+       instance breaks things. */
+    struct ap_filter_t *filter = r->output_filters;
+
+    while (filter) {
+        if (!strcasecmp("INCLUDES", filter->frec->name)) {
+            return DECLINED;
+        }
+        filter = filter->next;
+    }
+
     conf = ap_get_module_config(r->per_dir_config, &include_module);
 
     if (r->handler && (strcmp(r->handler, "server-parsed") == 0))