diff --git a/src/backend/executor/nodeHash.c b/src/backend/executor/nodeHash.c
index 6917d3f..e72ac8b 100644
--- a/src/backend/executor/nodeHash.c
+++ b/src/backend/executor/nodeHash.c
@@ -475,6 +475,7 @@ ExecChooseHashTableSize(double ntuples, int tupwidth, bool useskew,
 
 		lbuckets = (hash_table_bytes / tupsize) / NTUP_PER_BUCKET;
 		lbuckets = Min(lbuckets, max_pointers);
+		lbuckets = Min(lbuckets, MaxAllocSize / sizeof(void*));
 		nbuckets = (int) lbuckets;
 
 		dbatch = ceil(inner_rel_bytes / hash_table_bytes);
@@ -491,6 +492,7 @@ ExecChooseHashTableSize(double ntuples, int tupwidth, bool useskew,
 
 		dbuckets = ceil(ntuples / NTUP_PER_BUCKET);
 		dbuckets = Min(dbuckets, max_pointers);
+		dbuckets = Min(dbuckets, MaxAllocSize / sizeof(void*));
 		nbuckets = (int) dbuckets;
 
 		nbatch = 1;
@@ -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.)
 	 */