diff --git a/storage/innodb_plugin/include/rem0cmp.h b/storage/innodb_plugin/include/rem0cmp.h
index 072f742..82a70aa 100644
--- a/storage/innodb_plugin/include/rem0cmp.h
+++ b/storage/innodb_plugin/include/rem0cmp.h
@@ -148,7 +148,9 @@ cmp_rec_rec_simple(
 	const rec_t*		rec2,	/*!< in: physical record */
 	const ulint*		offsets1,/*!< in: rec_get_offsets(rec1, ...) */
 	const ulint*		offsets2,/*!< in: rec_get_offsets(rec2, ...) */
-	const dict_index_t*	index);	/*!< in: data dictionary index */
+	const dict_index_t*	index,	/*!< in: data dictionary index */
+	ibool*			null_eq);/*!< out: set to true if
+					found matching null values */
 /*************************************************************//**
 This function is used to compare two physical records. Only the common
 first fields are compared, and if an externally stored field is
diff --git a/storage/innodb_plugin/rem/rem0cmp.c b/storage/innodb_plugin/rem/rem0cmp.c
index e6dab0b..5c2bcbb 100644
--- a/storage/innodb_plugin/rem/rem0cmp.c
+++ b/storage/innodb_plugin/rem/rem0cmp.c
@@ -706,7 +706,9 @@ cmp_rec_rec_simple(
 	const rec_t*		rec2,	/*!< in: physical record */
 	const ulint*		offsets1,/*!< in: rec_get_offsets(rec1, ...) */
 	const ulint*		offsets2,/*!< in: rec_get_offsets(rec2, ...) */
-	const dict_index_t*	index)	/*!< in: data dictionary index */
+	const dict_index_t*	index,	/*!< in: data dictionary index */
+	ibool*			null_eq)/*!< out: set to true if
+					found matching null values */
 {
 	ulint		rec1_f_len;	/*!< length of current field in rec1 */
 	const byte*	rec1_b_ptr;	/*!< pointer to the current byte
@@ -727,6 +729,10 @@ cmp_rec_rec_simple(
 
 	ut_ad(rec_offs_comp(offsets1) == rec_offs_comp(offsets2));
 
+	if (null_eq) {
+		*null_eq = 0;
+	}
+
 	for (cur_field = 0; cur_field < n_uniq; cur_field++) {
 
 		ulint	cur_bytes;
@@ -753,6 +759,9 @@ cmp_rec_rec_simple(
 		    || rec2_f_len == UNIV_SQL_NULL) {
 
 			if (rec1_f_len == rec2_f_len) {
+				if (null_eq) {
+					*null_eq = 1;
+				}
 
 				goto next_field;
 
diff --git a/storage/innodb_plugin/row/row0merge.c b/storage/innodb_plugin/row/row0merge.c
index 88a2770..77233ae 100644
--- a/storage/innodb_plugin/row/row0merge.c
+++ b/storage/innodb_plugin/row/row0merge.c
@@ -1075,11 +1075,13 @@ row_merge_cmp(
 						record to be compared */
 	const ulint*		offsets1,	/*!< in: first record offsets */
 	const ulint*		offsets2,	/*!< in: second record offsets */
-	const dict_index_t*	index)		/*!< in: index */
+	const dict_index_t*	index,		/*!< in: index */
+	ibool*			null_eq)	/*!< out: set to true if
+						found matching null values */
 {
 	int	cmp;
 
-	cmp = cmp_rec_rec_simple(mrec1, mrec2, offsets1, offsets2, index);
+	cmp = cmp_rec_rec_simple(mrec1, mrec2, offsets1, offsets2, index, null_eq);
 
 #ifdef UNIV_DEBUG
 	if (row_merge_print_cmp) {
@@ -1445,11 +1447,13 @@ corrupt:
 	}
 
 	while (mrec0 && mrec1) {
+		ibool null_eq = 0;
 		switch (row_merge_cmp(mrec0, mrec1,
-				      offsets0, offsets1, index)) {
+				      offsets0, offsets1, index,
+				      &null_eq)) {
 		case 0:
 			if (UNIV_UNLIKELY
-			    (dict_index_is_unique(index))) {
+			    (dict_index_is_unique(index) && !null_eq)) {
 				innobase_rec_to_mysql(table, mrec0,
 						      index, offsets0);
 				mem_heap_free(heap);