diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index 6917d3f..ca90aed 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -465,6 +465,8 @@ ExecChooseHashTableSize(double ntuples, int tupwidth, bool useskew,
 	max_pointers = (work_mem * 1024L) / sizeof(void *);
 	/* also ensure we avoid integer overflow in nbatch and nbuckets */
 	max_pointers = Min(max_pointers, INT_MAX / 2);
+	/* ensure we don't exceed the maximum allocation size */
+	max_pointers = Min(max_pointers, MaxAllocSize / sizeof(void*));
 
 	if (inner_rel_bytes > hash_table_bytes)
 	{
@@ -500,7 +502,8 @@ ExecChooseHashTableSize(double ntuples, int tupwidth, bool useskew,
 	 * Both nbuckets and nbatch must be powers of 2 to make
 	 * ExecHashGetBucketAndBatch fast.  We already fixed nbatch; now inflate
 	 * nbuckets to the next larger power of 2.  We also force nbuckets to not
-	 * be real small, by starting the search at 2^10.  (Note: above we made
+	 * be real small, by starting the search at 2^10, or too large - we allocate
+	 * them as a single chunk, so must fit in MaxAllocSize. (Note: above we made
 	 * sure that nbuckets is not more than INT_MAX / 2, so this loop cannot
 	 * overflow, nor can the final shift to recalculate nbuckets.)
 	 */