diff --git a/src/backend/port/sysv_shmem.c b/src/backend/port/sysv_shmem.c
index de491897118..53f7a64fa45 100644
--- a/src/backend/port/sysv_shmem.c
+++ b/src/backend/port/sysv_shmem.c
@@ -617,7 +617,7 @@ CreateAnonymousSegment(Size *size)
 		GetHugePageSize(&hugepagesize, &mmap_flags);
 
 		if (allocsize % hugepagesize != 0)
-			allocsize += hugepagesize - (allocsize % hugepagesize);
+			allocsize = add_size(allocsize, hugepagesize - (allocsize % hugepagesize));
 
 		ptr = mmap(NULL, allocsize, PROT_READ | PROT_WRITE,
 				   PG_MMAP_FLAGS | mmap_flags, -1, 0);
diff --git a/src/backend/storage/ipc/ipci.c b/src/backend/storage/ipc/ipci.c
index 85c67b2c183..2a3dfedf7e9 100644
--- a/src/backend/storage/ipc/ipci.c
+++ b/src/backend/storage/ipc/ipci.c
@@ -363,7 +363,9 @@ InitializeShmemGUCs(void)
 	{
 		Size		hp_required;
 
-		hp_required = add_size(size_b / hp_size, 1);
+		hp_required = size_b / hp_size;
+		if (size_b % hp_size != 0)
+			hp_required = add_size(hp_required, 1);
 		sprintf(buf, "%zu", hp_required);
 		SetConfigOption("shared_memory_size_in_huge_pages", buf,
 						PGC_INTERNAL, PGC_S_DYNAMIC_DEFAULT);