diff --git a/src/backend/access/common/tidstore.c b/src/backend/access/common/tidstore.c
index cddbaf013b..78730797d6 100644
--- a/src/backend/access/common/tidstore.c
+++ b/src/backend/access/common/tidstore.c
@@ -43,35 +43,30 @@
  */
 typedef struct BlocktableEntry
 {
-	union
+	struct
 	{
-		struct
-		{
 #ifndef WORDS_BIGENDIAN
-			/*
-			 * We need to position this member so that the backing radix tree
-			 * can use the lowest bit for a pointer tag. In particular, it
-			 * must be placed within 'header' so that it corresponds to the
-			 * lowest byte in 'ptr'. We position 'nwords' along with it to
-			 * avoid struct padding.
-			 */
-			uint8		flags;
-
-			int8		nwords;
+		/*
+		 * We need to position this member so that the backing radix tree can
+		 * use the lowest bit for a pointer tag. In particular, it must be
+		 * placed within 'header' so that it corresponds to the lowest byte in
+		 * 'ptr'. We position 'nwords' along with it to avoid struct padding.
+		 */
+		uint8		flags;
+
+		int8		nwords;
 #endif
 
-			/*
-			 * We can store a small number of offsets here to avoid wasting
-			 * space with a sparse bitmap.
-			 */
-			OffsetNumber full_offsets[NUM_FULL_OFFSETS];
+		/*
+		 * We can store a small number of offsets here to avoid wasting space
+		 * with a sparse bitmap.
+		 */
+		OffsetNumber full_offsets[NUM_FULL_OFFSETS];
 
 #ifdef WORDS_BIGENDIAN
-			int8		nwords;
-			uint8		flags;
+		int8		nwords;
+		uint8		flags;
 #endif
-		};
-		uintptr_t	ptr;
 	}			header;
 
 	bitmapword	words[FLEXIBLE_ARRAY_MEMBER];