diff --git a/doc/man/man5/slapd-bdb.5 b/doc/man/man5/slapd-bdb.5
index ec3210e0ae..f0a6d4cf92 100644
--- a/doc/man/man5/slapd-bdb.5
+++ b/doc/man/man5/slapd-bdb.5
@@ -147,7 +147,10 @@ will return a different result.
 .BI dncachesize \ <integer>
 Specify the maximum number of DNs in the in-memory DN cache. The
 default is twice the \fBcachesize\fP. Ideally this cache should be
-large enough to contain the DNs of every entry in the database.
+large enough to contain the DNs of every entry in the database. If
+set to a smaller value than the \fBcachesize\fP it will be silently
+increased to equal the \fBcachesize\fP.
+
 It should be noted that the \fBDN cache\fP is allowed to temporarily
 grow beyond the configured size. It does this if many entries are 
 locked when it tries to do a purge, because that means they're
diff --git a/servers/slapd/back-bdb/init.c b/servers/slapd/back-bdb/init.c
index 653d0e9e78..fe480e59a9 100644
--- a/servers/slapd/back-bdb/init.c
+++ b/servers/slapd/back-bdb/init.c
@@ -374,6 +374,11 @@ shm_retry:
 		bdb->bi_cache.c_eimax = bdb->bi_cache.c_maxsize * 2;
 	}
 
+	/* dncache must be >= entrycache */
+	if ( bdb->bi_cache.c_eimax < bdb->bi_cache.c_maxsize ) {
+		bdb->bi_cache.c_eimax = bdb->bi_cache.c_maxsize;
+	}
+
 	if ( bdb->bi_idl_cache_max_size ) {
 		bdb->bi_idl_tree = NULL;
 		bdb->bi_idl_cache_size = 0;