diff --git a/src/backend/access/gin/gininsert.c b/src/backend/access/gin/gininsert.c
index 16abb76c001..e964f860ab7 100644
--- a/src/backend/access/gin/gininsert.c
+++ b/src/backend/access/gin/gininsert.c
@@ -2250,7 +2250,7 @@ _gin_build_tuple(OffsetNumber attrnum, unsigned char category,
 	char	   *ptr;
 
 	Size		tuplen;
-	int			keylen;
+	Size		keylen;
 
 	dlist_mutable_iter iter;
 	dlist_head	segments;
diff --git a/src/include/access/gin_tuple.h b/src/include/access/gin_tuple.h
index 7bde05e2de4..d2c7b50d1de 100644
--- a/src/include/access/gin_tuple.h
+++ b/src/include/access/gin_tuple.h
@@ -23,12 +23,17 @@ typedef struct GinTuple
 {
 	int			tuplen;			/* length of the whole tuple */
 	OffsetNumber attrnum;		/* attnum of index key */
-	uint16		keylen;			/* bytes in data for key value */
+	Size		keylen;			/* bytes in data for key value */
 	int16		typlen;			/* typlen for key */
 	bool		typbyval;		/* typbyval for key */
 	signed char category;		/* category: normal or NULL? */
 	int			nitems;			/* number of TIDs in the data */
-	char		data[FLEXIBLE_ARRAY_MEMBER];
+
+	/*
+	 * The key value is accessed in place, so it must be aligned well enough
+	 * for any key type.
+	 */
+	char		alignas(MAXIMUM_ALIGNOF) data[FLEXIBLE_ARRAY_MEMBER];
 } GinTuple;
 
 static inline ItemPointer