diff --git a/src/backend/access/transam/parallel.c b/src/backend/access/transam/parallel.c
index 0bba9a7..07e4ae0 100644
--- a/src/backend/access/transam/parallel.c
+++ b/src/backend/access/transam/parallel.c
@@ -241,7 +241,7 @@ InitializeParallelDSM(ParallelContext *pcxt)
 						 PARALLEL_ERROR_QUEUE_SIZE,
 						 "parallel error queue size not buffer-aligned");
 		shm_toc_estimate_chunk(&pcxt->estimator,
-							   PARALLEL_ERROR_QUEUE_SIZE * pcxt->nworkers);
+							   PARALLEL_ERROR_QUEUE_SIZE * (Size)pcxt->nworkers);
 		shm_toc_estimate_keys(&pcxt->estimator, 1);
 
 		/* Estimate how much we'll need for extension entrypoint info. */
@@ -347,7 +347,7 @@ InitializeParallelDSM(ParallelContext *pcxt)
 		 */
 		error_queue_space =
 			shm_toc_allocate(pcxt->toc,
-							 PARALLEL_ERROR_QUEUE_SIZE * pcxt->nworkers);
+							 PARALLEL_ERROR_QUEUE_SIZE * (Size)pcxt->nworkers);
 		for (i = 0; i < pcxt->nworkers; ++i)
 		{
 			char	   *start;
diff --git a/src/backend/executor/execParallel.c b/src/backend/executor/execParallel.c
index 6df62a7..a90e82c 100644
--- a/src/backend/executor/execParallel.c
+++ b/src/backend/executor/execParallel.c
@@ -278,7 +278,7 @@ ExecParallelSetupTupleQueues(ParallelContext *pcxt, bool reinitialize)
 
 	/* Allocate memory for shared memory queue handles. */
 	responseq = (shm_mq_handle **)
-		palloc(pcxt->nworkers * sizeof(shm_mq_handle *));
+		palloc((Size)pcxt->nworkers * sizeof(shm_mq_handle *));
 
 	/*
 	 * If not reinitializing, allocate space from the DSM for the queues;
@@ -287,7 +287,7 @@ ExecParallelSetupTupleQueues(ParallelContext *pcxt, bool reinitialize)
 	if (!reinitialize)
 		tqueuespace =
 			shm_toc_allocate(pcxt->toc,
-							 PARALLEL_TUPLE_QUEUE_SIZE * pcxt->nworkers);
+							 PARALLEL_TUPLE_QUEUE_SIZE * (Size)pcxt->nworkers);
 	else
 		tqueuespace = shm_toc_lookup(pcxt->toc, PARALLEL_KEY_TUPLE_QUEUE);
 
@@ -296,7 +296,7 @@ ExecParallelSetupTupleQueues(ParallelContext *pcxt, bool reinitialize)
 	{
 		shm_mq	   *mq;
 
-		mq = shm_mq_create(tqueuespace + i * PARALLEL_TUPLE_QUEUE_SIZE,
+		mq = shm_mq_create(tqueuespace + (Size)i * PARALLEL_TUPLE_QUEUE_SIZE,
 						   (Size) PARALLEL_TUPLE_QUEUE_SIZE);
 
 		shm_mq_set_receiver(mq, MyProc);
@@ -380,12 +380,12 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate, int nworkers)
 	 * looking at pgBufferUsage, so do it unconditionally.
 	 */
 	shm_toc_estimate_chunk(&pcxt->estimator,
-						   sizeof(BufferUsage) * pcxt->nworkers);
+						   sizeof(BufferUsage) * (Size)pcxt->nworkers);
 	shm_toc_estimate_keys(&pcxt->estimator, 1);
 
 	/* Estimate space for tuple queues. */
 	shm_toc_estimate_chunk(&pcxt->estimator,
-						   PARALLEL_TUPLE_QUEUE_SIZE * pcxt->nworkers);
+						   PARALLEL_TUPLE_QUEUE_SIZE * (Size)pcxt->nworkers);
 	shm_toc_estimate_keys(&pcxt->estimator, 1);
 
 	/*
@@ -432,7 +432,7 @@ ExecInitParallelPlan(PlanState *planstate, EState *estate, int nworkers)
 
 	/* Allocate space for each worker's BufferUsage; no need to initialize. */
 	bufusage_space = shm_toc_allocate(pcxt->toc,
-									  sizeof(BufferUsage) * pcxt->nworkers);
+								sizeof(BufferUsage) * (Size)pcxt->nworkers);
 	shm_toc_insert(pcxt->toc, PARALLEL_KEY_BUFFER_USAGE, bufusage_space);
 	pei->buffer_usage = bufusage_space;