diff --git a/contrib/btree_gist/btree_cash.c b/contrib/btree_gist/btree_cash.c
index 8de3716c945..63f86ebeefe 100644
--- a/contrib/btree_gist/btree_cash.c
+++ b/contrib/btree_gist/btree_cash.c
@@ -78,6 +78,7 @@ static const gbtree_ninfo tinfo =
 {
 	gbt_t_cash,
 	sizeof(Cash),
+	16,							/* sizeof(gbtreekey16) */
 	gbt_cashgt,
 	gbt_cashge,
 	gbt_casheq,
diff --git a/contrib/btree_gist/btree_date.c b/contrib/btree_gist/btree_date.c
index 9cab7ec42f5..7a4c6aa6003 100644
--- a/contrib/btree_gist/btree_date.c
+++ b/contrib/btree_gist/btree_date.c
@@ -96,6 +96,7 @@ static const gbtree_ninfo tinfo =
 {
 	gbt_t_date,
 	sizeof(DateADT),
+	8,							/* sizeof(gbtreekey8) */
 	gbt_dategt,
 	gbt_datege,
 	gbt_dateeq,
diff --git a/contrib/btree_gist/btree_float4.c b/contrib/btree_gist/btree_float4.c
index 55e1c4c1c6d..778d8dad844 100644
--- a/contrib/btree_gist/btree_float4.c
+++ b/contrib/btree_gist/btree_float4.c
@@ -77,6 +77,7 @@ static const gbtree_ninfo tinfo =
 {
 	gbt_t_float4,
 	sizeof(float4),
+	8,							/* sizeof(gbtreekey8) */
 	gbt_float4gt,
 	gbt_float4ge,
 	gbt_float4eq,
diff --git a/contrib/btree_gist/btree_float8.c b/contrib/btree_gist/btree_float8.c
index 62271dec84a..c898bf2d975 100644
--- a/contrib/btree_gist/btree_float8.c
+++ b/contrib/btree_gist/btree_float8.c
@@ -85,6 +85,7 @@ static const gbtree_ninfo tinfo =
 {
 	gbt_t_float8,
 	sizeof(float8),
+	16,							/* sizeof(gbtreekey16) */
 	gbt_float8gt,
 	gbt_float8ge,
 	gbt_float8eq,
diff --git a/contrib/btree_gist/btree_inet.c b/contrib/btree_gist/btree_inet.c
index 24ae6bf3693..822786125d9 100644
--- a/contrib/btree_gist/btree_inet.c
+++ b/contrib/btree_gist/btree_inet.c
@@ -74,6 +74,7 @@ static const gbtree_ninfo tinfo =
 {
 	gbt_t_inet,
 	sizeof(double),
+	16,							/* sizeof(gbtreekey16) */
 	gbt_inetgt,
 	gbt_inetge,
 	gbt_ineteq,
diff --git a/contrib/btree_gist/btree_int2.c b/contrib/btree_gist/btree_int2.c
index d51ad0c2ab2..a88aae64537 100644
--- a/contrib/btree_gist/btree_int2.c
+++ b/contrib/btree_gist/btree_int2.c
@@ -77,6 +77,7 @@ static const gbtree_ninfo tinfo =
 {
 	gbt_t_int2,
 	sizeof(int16),
+	4,							/* sizeof(gbtreekey4) */
 	gbt_int2gt,
 	gbt_int2ge,
 	gbt_int2eq,
diff --git a/contrib/btree_gist/btree_int4.c b/contrib/btree_gist/btree_int4.c
index e7641f22847..889a5120783 100644
--- a/contrib/btree_gist/btree_int4.c
+++ b/contrib/btree_gist/btree_int4.c
@@ -78,6 +78,7 @@ static const gbtree_ninfo tinfo =
 {
 	gbt_t_int4,
 	sizeof(int32),
+	8,							/* sizeof(gbtreekey8) */
 	gbt_int4gt,
 	gbt_int4ge,
 	gbt_int4eq,
diff --git a/contrib/btree_gist/btree_int8.c b/contrib/btree_gist/btree_int8.c
index 8bc8cb5fdf7..8685cee1760 100644
--- a/contrib/btree_gist/btree_int8.c
+++ b/contrib/btree_gist/btree_int8.c
@@ -78,6 +78,7 @@ static const gbtree_ninfo tinfo =
 {
 	gbt_t_int8,
 	sizeof(int64),
+	16,							/* sizeof(gbtreekey16) */
 	gbt_int8gt,
 	gbt_int8ge,
 	gbt_int8eq,
diff --git a/contrib/btree_gist/btree_interval.c b/contrib/btree_gist/btree_interval.c
index 93a341eb77e..68d80e8e0ae 100644
--- a/contrib/btree_gist/btree_interval.c
+++ b/contrib/btree_gist/btree_interval.c
@@ -87,7 +87,9 @@ gbt_intv_dist(const void *a, const void *b)
 /*
  * INTERVALSIZE should be the actual size-on-disk of an Interval, as shown
  * in pg_type.  This might be less than sizeof(Interval) if the compiler
- * insists on adding alignment padding at the end of the struct.
+ * insists on adding alignment padding at the end of the struct.  (Note:
+ * this concern is obsolete with the current definition of Interval, but
+ * was real before a separate "day" field was added to it.)
  */
 #define INTERVALSIZE 16
 
@@ -95,6 +97,7 @@ static const gbtree_ninfo tinfo =
 {
 	gbt_t_intv,
 	sizeof(Interval),
+	32,							/* sizeof(gbtreekey32) */
 	gbt_intvgt,
 	gbt_intvge,
 	gbt_intveq,
diff --git a/contrib/btree_gist/btree_macaddr.c b/contrib/btree_gist/btree_macaddr.c
index 6255564ac5a..244b95154bb 100644
--- a/contrib/btree_gist/btree_macaddr.c
+++ b/contrib/btree_gist/btree_macaddr.c
@@ -74,6 +74,7 @@ static const gbtree_ninfo tinfo =
 {
 	gbt_t_macad,
 	sizeof(macaddr),
+	16,							/* sizeof(gbtreekey16) */
 	gbt_macadgt,
 	gbt_macadge,
 	gbt_macadeq,
diff --git a/contrib/btree_gist/btree_oid.c b/contrib/btree_gist/btree_oid.c
index dcd0765417b..f6b7bfa05b7 100644
--- a/contrib/btree_gist/btree_oid.c
+++ b/contrib/btree_gist/btree_oid.c
@@ -84,6 +84,7 @@ static const gbtree_ninfo tinfo =
 {
 	gbt_t_oid,
 	sizeof(Oid),
+	8,							/* sizeof(gbtreekey8) */
 	gbt_oidgt,
 	gbt_oidge,
 	gbt_oideq,
diff --git a/contrib/btree_gist/btree_time.c b/contrib/btree_gist/btree_time.c
index e0e32428e22..cdf81711e76 100644
--- a/contrib/btree_gist/btree_time.c
+++ b/contrib/btree_gist/btree_time.c
@@ -124,6 +124,7 @@ static const gbtree_ninfo tinfo =
 {
 	gbt_t_time,
 	sizeof(TimeADT),
+	16,							/* sizeof(gbtreekey16) */
 	gbt_timegt,
 	gbt_timege,
 	gbt_timeeq,
diff --git a/contrib/btree_gist/btree_ts.c b/contrib/btree_gist/btree_ts.c
index 10f325d6720..a13dcc8beaa 100644
--- a/contrib/btree_gist/btree_ts.c
+++ b/contrib/btree_gist/btree_ts.c
@@ -127,6 +127,7 @@ static const gbtree_ninfo tinfo =
 {
 	gbt_t_ts,
 	sizeof(Timestamp),
+	16,							/* sizeof(gbtreekey16) */
 	gbt_tsgt,
 	gbt_tsge,
 	gbt_tseq,
diff --git a/contrib/btree_gist/btree_utils_num.c b/contrib/btree_gist/btree_utils_num.c
index 5e52ab542bf..505633c98b8 100644
--- a/contrib/btree_gist/btree_utils_num.c
+++ b/contrib/btree_gist/btree_utils_num.c
@@ -28,7 +28,7 @@ gbt_num_compress(GISTENTRY *retval, GISTENTRY *entry, const gbtree_ninfo *tinfo)
 			Cash		ch;
 		}			v;
 
-		GBT_NUMKEY *r = (GBT_NUMKEY *) palloc0(2 * tinfo->size);
+		GBT_NUMKEY *r = (GBT_NUMKEY *) palloc0(tinfo->indexsize);
 		void	   *leaf = NULL;
 
 		switch (tinfo->t)
@@ -77,6 +77,8 @@ gbt_num_compress(GISTENTRY *retval, GISTENTRY *entry, const gbtree_ninfo *tinfo)
 				leaf = DatumGetPointer(entry->key);
 		}
 
+		Assert(tinfo->indexsize >= 2 * tinfo->size);
+
 		memcpy((void *) &r[0], leaf, tinfo->size);
 		memcpy((void *) &r[tinfo->size], leaf, tinfo->size);
 		retval = palloc(sizeof(GISTENTRY));
@@ -165,7 +167,7 @@ gbt_num_bin_union(Datum *u, GBT_NUMKEY *e, const gbtree_ninfo *tinfo)
 
 	if (!DatumGetPointer(*u))
 	{
-		*u = PointerGetDatum(palloc(2 * tinfo->size));
+		*u = PointerGetDatum(palloc0(tinfo->indexsize));
 		memcpy((void *) &(((GBT_NUMKEY *) DatumGetPointer(*u))[0]), (void *) rd.lower, tinfo->size);
 		memcpy((void *) &(((GBT_NUMKEY *) DatumGetPointer(*u))[tinfo->size]), (void *) rd.upper, tinfo->size);
 	}
diff --git a/contrib/btree_gist/btree_utils_num.h b/contrib/btree_gist/btree_utils_num.h
index d7a61d22426..0d79cd2a7f7 100644
--- a/contrib/btree_gist/btree_utils_num.h
+++ b/contrib/btree_gist/btree_utils_num.h
@@ -37,7 +37,8 @@ typedef struct
 	/* Attribs */
 
 	enum gbtree_type t;			/* data type */
-	int32		size;			/* size of type , 0 means variable */
+	int32		size;			/* size of type, 0 means variable */
+	int32		indexsize;		/* size of datums stored in index */
 
 	/* Methods */