diff --git a/src/structs.h b/src/structs.h
index 3b24eec..fedd3b9 100644
--- a/src/structs.h
+++ b/src/structs.h
@@ -1203,10 +1203,11 @@
 
 typedef struct dictitem_S dictitem_T;
 
-#define DI_FLAGS_RO	1 /* "di_flags" value: read-only variable */
-#define DI_FLAGS_RO_SBX 2 /* "di_flags" value: read-only in the sandbox */
-#define DI_FLAGS_FIX	4 /* "di_flags" value: fixed variable, not allocated */
-#define DI_FLAGS_LOCK	8 /* "di_flags" value: locked variable */
+#define DI_FLAGS_RO	1  /* "di_flags" value: read-only variable */
+#define DI_FLAGS_RO_SBX 2  /* "di_flags" value: read-only in the sandbox */
+#define DI_FLAGS_FIX	4  /* "di_flags" value: fixed: no :unlet or remove() */
+#define DI_FLAGS_LOCK	8  /* "di_flags" value: locked variable */
+#define DI_FLAGS_ALLOC	16 /* "di_flags" value: separately allocated */
 
 /*
  * Structure to hold info about a Dictionary.