3 files changed, 6 insertions, 10 deletions

diff --git a/compile.c b/compile.c
index 87a1bd8f6a..6fae343d78 100644
--- a/compile.c
+++ b/compile.c
@@ -868,7 +868,7 @@ compile_data_alloc(rb_iseq_t *iseq, size_t size)
 	    alloc_size *= 2;
 	}
 	storage->next = (void *)ALLOC_N(char, alloc_size +
-					SIZEOF_ISEQ_COMPILE_DATA_STORAGE);
+					sizeof(struct iseq_compile_data_storage));
 	storage = ISEQ_COMPILE_DATA(iseq)->storage_current = storage->next;
 	storage->next = 0;
 	storage->pos = 0;
diff --git a/iseq.c b/iseq.c
index ee49026c9a..57ff506d0a 100644
--- a/iseq.c
+++ b/iseq.c
@@ -208,7 +208,7 @@ iseq_memsize(const rb_iseq_t *iseq)
 
 	cur = compile_data->storage_head;
 	while (cur) {
-	    size += cur->size + SIZEOF_ISEQ_COMPILE_DATA_STORAGE;
+	    size += cur->size + sizeof(struct iseq_compile_data_storage);
 	    cur = cur->next;
 	}
     }
@@ -333,7 +333,7 @@ prepare_iseq_build(rb_iseq_t *iseq,
     ISEQ_COMPILE_DATA(iseq)->storage_head = ISEQ_COMPILE_DATA(iseq)->storage_current =
       (struct iseq_compile_data_storage *)
 	ALLOC_N(char, INITIAL_ISEQ_COMPILE_DATA_STORAGE_BUFF_SIZE +
-		SIZEOF_ISEQ_COMPILE_DATA_STORAGE);
+		sizeof(struct iseq_compile_data_storage));
 
     RB_OBJ_WRITE(iseq, &ISEQ_COMPILE_DATA(iseq)->catch_table_ary, rb_ary_tmp_new(3));
     ISEQ_COMPILE_DATA(iseq)->storage_head->pos = 0;
diff --git a/iseq.h b/iseq.h
index 639d12bf24..daeac0c889 100644
--- a/iseq.h
+++ b/iseq.h
@@ -249,7 +249,7 @@ struct iseq_catch_table_entry {
 
 PACKED_STRUCT_UNALIGNED(struct iseq_catch_table {
     unsigned int size;
-    struct iseq_catch_table_entry entries[1]; /* flexible array */
+    struct iseq_catch_table_entry entries[FLEX_ARY_LEN];
 });
 
 static inline int
@@ -260,7 +260,7 @@ iseq_catch_table_bytes(int n)
     };
     if (n > catch_table_entries_max) rb_fatal("too large iseq_catch_table - %d", n);
     return (int)(sizeof(struct iseq_catch_table) +
-		 (n - 1) * sizeof(struct iseq_catch_table_entry));
+		 n * sizeof(struct iseq_catch_table_entry));
 }
 
 #define INITIAL_ISEQ_COMPILE_DATA_STORAGE_BUFF_SIZE (512)
@@ -269,13 +269,9 @@ struct iseq_compile_data_storage {
     struct iseq_compile_data_storage *next;
     unsigned int pos;
     unsigned int size;
-    char buff[1]; /* flexible array */
+    char buff[FLEX_ARY_LEN];
 };
 
-/* account for flexible array */
-#define SIZEOF_ISEQ_COMPILE_DATA_STORAGE \
-    (sizeof(struct iseq_compile_data_storage) - 1)
-
 /* defined? */
 
 enum defined_type {