diff -rupN httpd-2.4.1/modules/aaa/mod_auth_digest.c httpd-2.4.1-edited/modules/aaa/mod_auth_digest.c
--- httpd-2.4.1/modules/aaa/mod_auth_digest.c	2011-12-04 18:08:01.000000000 -0600
+++ httpd-2.4.1-edited/modules/aaa/mod_auth_digest.c	2012-04-02 12:30:19.000000000 -0500
@@ -470,6 +470,38 @@ static void *create_digest_dir_config(ap
     return conf;
 }
 
+static void *merge_digest_dir_config(apr_pool_t *a, void *basev, void *newv)
+{
+    digest_config_rec *base = (digest_config_rec *)basev;
+    digest_config_rec *new = (digest_config_rec *)newv;
+    digest_config_rec *conf =
+        (digest_config_rec *)apr_pcalloc(a, sizeof(digest_config_rec));
+	
+	/* Always take the new value */
+	conf->qop_list = new->qop_list;
+	conf->nonce_lifetime = new->nonce_lifetime;
+	conf->dir_name = new->dir_name;
+	conf->algorithm = new->algorithm;
+	conf->providers = new->providers;
+	conf->nonce_format = new->nonce_format;
+	conf->check_nc = new->check_nc;
+	conf->uri_list = new->uri_list;
+	conf->ha1 = new->ha1;
+	
+	/* Except for the realm name,  match mod_authn_core's merge rules here */
+	/* Also pass forward the precalculated nonce_ctx */		
+    if (new->realm) {
+        conf->realm = new->realm;
+		conf->nonce_ctx = new->nonce_ctx;
+    } else {
+        conf->realm = base->realm;
+		conf->nonce_ctx = base->nonce_ctx;
+    }
+
+    return (void*)conf;
+}
+
+
 static const char *set_realm(cmd_parms *cmd, void *config, const char *realm)
 {
     digest_config_rec *conf = (digest_config_rec *) config;
@@ -1843,7 +1875,7 @@ static int authenticate_digest_user(requ
         return HTTP_UNAUTHORIZED;
     }
 
-    if (strcmp(resp->realm, conf->realm)) {
+    if (resp->realm == NULL || conf->realm == NULL || strcmp(resp->realm, conf->realm)) {
         ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(01788)
                       "realm mismatch - got `%s' but expected `%s'",
                       resp->realm, conf->realm);
@@ -2084,7 +2116,7 @@ AP_DECLARE_MODULE(auth_digest) =
 {
     STANDARD20_MODULE_STUFF,
     create_digest_dir_config,   /* dir config creater */
-    NULL,                       /* dir merger --- default is to override */
+    merge_digest_dir_config,    /* dir merger --- default is to override */
     NULL,                       /* server config */
     NULL,                       /* merge server config */
     digest_cmds,                /* command table */