diff --git a/src/backend/access/hash/hash.c b/src/backend/access/hash/hash.c
index 49a6c816aa..19695ee102 100644
--- a/src/backend/access/hash/hash.c
+++ b/src/backend/access/hash/hash.c
@@ -176,19 +176,25 @@ hashbuildCallback(Relation index,
 				  void *state)
 {
 	HashBuildState *buildstate = (HashBuildState *) state;
+	Datum		index_values[1];
+	bool		index_isnull[1];
 	IndexTuple	itup;
 
-	/* Hash indexes don't index nulls, see notes in hashinsert */
-	if (isnull[0])
+	/* convert data to a hash key; on failure, do not insert anything */
+	if (!_hash_convert_tuple(index,
+							 values, isnull,
+							 index_values, index_isnull))
 		return;
 
 	/* Either spool the tuple for sorting, or just put it into the index */
 	if (buildstate->spool)
-		_h_spool(buildstate->spool, &htup->t_self, values, isnull);
+		_h_spool(buildstate->spool, &htup->t_self,
+				 index_values, index_isnull);
 	else
 	{
 		/* form an index tuple and point it at the heap tuple */
-		itup = _hash_form_tuple(index, values, isnull);
+		itup = index_form_tuple(RelationGetDescr(index),
+								index_values, index_isnull);
 		itup->t_tid = htup->t_self;
 		_hash_doinsert(index, itup);
 		pfree(itup);
@@ -208,22 +214,18 @@ hashinsert(Relation rel, Datum *values, bool *isnull,
 		   ItemPointer ht_ctid, Relation heapRel,
 		   IndexUniqueCheck checkUnique)
 {
+	Datum		index_values[1];
+	bool		index_isnull[1];
 	IndexTuple	itup;
 
-	/*
-	 * If the single index key is null, we don't insert it into the index.
-	 * Hash tables support scans on '='. Relational algebra says that A = B
-	 * returns null if either A or B is null.  This means that no
-	 * qualification used in an index scan could ever return true on a null
-	 * attribute.  It also means that indices can't be used by ISNULL or
-	 * NOTNULL scans, but that's an artifact of the strategy map architecture
-	 * chosen in 1986, not of the way nulls are handled here.
-	 */
-	if (isnull[0])
+	/* convert data to a hash key; on failure, do not insert anything */
+	if (!_hash_convert_tuple(rel,
+							 values, isnull,
+							 index_values, index_isnull))
 		return false;
 
-	/* generate an index tuple */
-	itup = _hash_form_tuple(rel, values, isnull);
+	/* form an index tuple and point it at the heap tuple */
+	itup = index_form_tuple(RelationGetDescr(rel), index_values, index_isnull);
 	itup->t_tid = *ht_ctid;
 
 	_hash_doinsert(rel, itup);
diff --git a/src/backend/access/hash/hashutil.c b/src/backend/access/hash/hashutil.c
index 456954b063..822862db7a 100644
--- a/src/backend/access/hash/hashutil.c
+++ b/src/backend/access/hash/hashutil.c
@@ -240,27 +240,37 @@ _hash_get_indextuple_hashkey(IndexTuple itup)
 }
 
 /*
- * _hash_form_tuple - form an index tuple containing hash code only
+ * _hash_convert_tuple - convert raw index data to hash key
+ *
+ * Inputs: values and isnull arrays for the user data column(s)
+ * Outputs: values and isnull arrays for the index tuple, suitable for
+ *		passing to index_form_tuple().
+ *
+ * Returns true if successful, false if not (because there are null values).
+ * On a false result, the given data need not be indexed.
+ *
+ * Note: callers know that the index-column arrays are always of length 1.
+ * In principle, there could be more than one input column, though we do not
+ * currently support that.
  */
-IndexTuple
-_hash_form_tuple(Relation index, Datum *values, bool *isnull)
+bool
+_hash_convert_tuple(Relation index,
+					Datum *user_values, bool *user_isnull,
+					Datum *index_values, bool *index_isnull)
 {
-	IndexTuple	itup;
 	uint32		hashkey;
-	Datum		hashkeydatum;
-	TupleDesc	hashdesc;
 
-	if (isnull[0])
-		hashkeydatum = (Datum) 0;
-	else
-	{
-		hashkey = _hash_datum2hashkey(index, values[0]);
-		hashkeydatum = UInt32GetDatum(hashkey);
-	}
-	hashdesc = RelationGetDescr(index);
-	Assert(hashdesc->natts == 1);
-	itup = index_form_tuple(hashdesc, &hashkeydatum, isnull);
-	return itup;
+	/*
+	 * We do not insert null values into hash indexes.  This is okay because
+	 * the only supported search operator is '=', and we assume it is strict.
+	 */
+	if (user_isnull[0])
+		return false;
+
+	hashkey = _hash_datum2hashkey(index, user_values[0]);
+	index_values[0] = UInt32GetDatum(hashkey);
+	index_isnull[0] = false;
+	return true;
 }
 
 /*
diff --git a/src/include/access/hash.h b/src/include/access/hash.h
index fa3f9b61ca..ce314180e6 100644
--- a/src/include/access/hash.h
+++ b/src/include/access/hash.h
@@ -359,8 +359,9 @@ extern Bucket _hash_hashkey2bucket(uint32 hashkey, uint32 maxbucket,
 extern uint32 _hash_log2(uint32 num);
 extern void _hash_checkpage(Relation rel, Buffer buf, int flags);
 extern uint32 _hash_get_indextuple_hashkey(IndexTuple itup);
-extern IndexTuple _hash_form_tuple(Relation index,
-				 Datum *values, bool *isnull);
+extern bool _hash_convert_tuple(Relation index,
+					Datum *user_values, bool *user_isnull,
+					Datum *index_values, bool *index_isnull);
 extern OffsetNumber _hash_binsearch(Page page, uint32 hash_value);
 extern OffsetNumber _hash_binsearch_last(Page page, uint32 hash_value);