diff --git a/CHANGES b/CHANGES
index 1b2d78315197be758e96b5d02c7fd661c4e6494a..9d54c4c91590ce1e18d755b29a71ee8521a26e57 100644
--- a/CHANGES
+++ b/CHANGES
@@ -17,6 +17,7 @@ OpenLDAP 2.4.17 Engineering
 	Fixed slapd cancel behavior (ITS#6137)
 	Fixed slapd cert validation (ITS#6098)
 	Fixed slapd connection_destroy assert (ITS#6089)
+	Fixed slapd csn normalization (ITS#6195)
 	Fixed slapd errno handling (ITS#6037)
 	Fixed slapd global alloc handling (ITS#6054)
 	Fixed slapd hung writers (ITS#5836)
diff --git a/servers/slapd/ldapsync.c b/servers/slapd/ldapsync.c
index f71bedaf45fdd18f831a3a4a94f0429c3a91916d..0e080301193557b4b32955558b3fe386fe98758c 100644
--- a/servers/slapd/ldapsync.c
+++ b/servers/slapd/ldapsync.c
@@ -176,7 +176,7 @@ slap_parse_sync_cookie(
 	char *csn_str;
 	char *cval;
 	char *next, *end;
-	AttributeDescription *ad = slap_schema.si_ad_modifyTimestamp;
+	AttributeDescription *ad = slap_schema.si_ad_entryCSN;
 
 	if ( cookie == NULL )
 		return -1;
@@ -230,13 +230,11 @@ slap_parse_sync_cookie(
 			continue;
 		}
 		if ( !strncmp( next, "csn=", STRLENOF("csn=") )) {
-			slap_syntax_validate_func *validate;
 			struct berval stamp;
 
 			next += STRLENOF("csn=");
 			while ( next < end ) {
 				csn_str = next;
-				/* FIXME use csnValidate when it gets implemented */
 				csn_ptr = strchr( csn_str, '#' );
 				if ( !csn_ptr || csn_ptr > end )
 					break;
@@ -244,14 +242,6 @@ slap_parse_sync_cookie(
 				 * want to parse the rid then. But we still iterate
 				 * through the string to find the end.
 				 */
-				if ( ad ) {
-					stamp.bv_val = csn_str;
-					stamp.bv_len = csn_ptr - csn_str;
-					validate = ad->ad_type->sat_syntax->ssyn_validate;
-					if ( validate( ad->ad_type->sat_syntax, &stamp )
-						!= LDAP_SUCCESS )
-						break;
-				}
 				cval = strchr( csn_ptr, ';' );
 				if ( !cval )
 					cval = strchr(csn_ptr, ',' );
@@ -261,7 +251,16 @@ slap_parse_sync_cookie(
 					stamp.bv_len = end - csn_str;
 				if ( ad ) {
 					struct berval bv;
-					ber_dupbv_x( &bv, &stamp, memctx );
+					stamp.bv_val = csn_str;
+					if ( ad->ad_type->sat_syntax->ssyn_validate(
+						ad->ad_type->sat_syntax, &stamp ) != LDAP_SUCCESS )
+						break;
+					if ( ad->ad_type->sat_equality->smr_normalize(
+						SLAP_MR_VALUE_OF_ATTRIBUTE_SYNTAX,
+						ad->ad_type->sat_syntax,
+						ad->ad_type->sat_equality,
+						&stamp, &bv, memctx ) != LDAP_SUCCESS )
+						break;
 					ber_bvarray_add_x( &cookie->ctxcsn, &bv, memctx );
 					cookie->numcsns++;
 				}