diff --git a/src/gc.c b/src/gc.c
index 79e7ba8fc..5e2eb88be 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -89,6 +89,7 @@ typedef struct {
 #ifdef ENABLE_STRUCT
     struct RStruct structdata;
 #endif
+    struct RData data;
     struct RProc procdata;
   } as;
 } RVALUE;