diff --git a/src/backend/access/brin/brin_minmax_multi.c b/src/backend/access/brin/brin_minmax_multi.c
index f8b2a3f9bc6..3d5e6d0c8f6 100644
--- a/src/backend/access/brin/brin_minmax_multi.c
+++ b/src/backend/access/brin/brin_minmax_multi.c
@@ -2084,10 +2084,13 @@ brin_minmax_multi_distance_date(PG_FUNCTION_ARGS)
 	DateADT		dateVal1 = PG_GETARG_DATEADT(0);
 	DateADT		dateVal2 = PG_GETARG_DATEADT(1);
 
-	if (DATE_NOT_FINITE(dateVal1) || DATE_NOT_FINITE(dateVal2))
-		PG_RETURN_FLOAT8(0);
+	/*
+	 * We know the values are range boundaries, but the range may be collapsed
+	 * (i.e. single points), with equal values.
+	 */
+	Assert(dateVal1 <= dateVal2);
 
-	PG_RETURN_FLOAT8(dateVal1 - dateVal2);
+	PG_RETURN_FLOAT8((double) dateVal2 - (double) dateVal1);
 }
 
 /*
@@ -2136,19 +2139,16 @@ brin_minmax_multi_distance_timetz(PG_FUNCTION_ARGS)
 Datum
 brin_minmax_multi_distance_timestamp(PG_FUNCTION_ARGS)
 {
-	float8		delta = 0;
-
 	Timestamp	dt1 = PG_GETARG_TIMESTAMP(0);
 	Timestamp	dt2 = PG_GETARG_TIMESTAMP(1);
 
-	if (TIMESTAMP_NOT_FINITE(dt1) || TIMESTAMP_NOT_FINITE(dt2))
-		PG_RETURN_FLOAT8(0);
-
-	delta = dt2 - dt1;
-
-	Assert(delta >= 0);
+	/*
+	 * We know the values are range boundaries, but the range may be collapsed
+	 * (i.e. single points), with equal values.
+	 */
+	Assert(dt1 <= dt2);
 
-	PG_RETURN_FLOAT8(delta);
+	PG_RETURN_FLOAT8((double) dt2 - (double) dt1);
 }
 
 /*