diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index 5e025a7437..c6286f08ab 100644
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -590,8 +590,10 @@ scalarineqsel(PlannerInfo *root, Oid operator, bool isgt, bool iseq,
 			block = ItemPointerGetBlockNumberNoCheck(itemptr);
 
 			/*
-			 * If there's a useable density (tuples per page) estimate, take
-			 * into account the fraction of a block with a lower TID offset.
+			 * Determine the average number of tuples per page.  We naively
+			 * assume there will never be any dead tuples or empty space at
+			 * the start or in the middle of the page.  This is likely fine
+			 * for the purposes here.
 			 */
 			density = vardata->rel->tuples / vardata->rel->pages;
 			if (density > 0.0)
@@ -603,10 +605,17 @@ scalarineqsel(PlannerInfo *root, Oid operator, bool isgt, bool iseq,
 
 			selec = block / (double) vardata->rel->pages;
 
-			/* For <= and >=, one extra item is included. */
-			if (iseq && vardata->rel->tuples >= 1.0)
-				selec += (1 / vardata->rel->tuples);
+			/*
+			 * We'll have one less tuple for "<" and one additional tuple for
+			 * ">=", the latter of which we'll reverse the selectivity for
+			 * below, so we can simply subtract a tuple here.  We can easily
+			 * detect these two cases by iseq being equal to isgt.  They'll
+			 * either both be true or both be false.
+			 */
+			if (iseq == isgt && vardata->rel->tuples >= 1.0)
+				selec -= (1 / vardata->rel->tuples);
 
+			/* Finally, reverse the selectivity for the ">", ">=" case. */
 			if (isgt)
 				selec = 1.0 - selec;